OUTER HOUSE, COURT OF SESSION
OPINION OF LORD NIMMO SMITH
in the cause
COFLEXIP STENA OFFSHORE LIMITED
Pursuers: Dean of Faculty, Clive; Simpson & Marwick, W.S.
Defenders: Currie, Q.C., Higgins; Maclay Murray & Spens
26 August 2003
 The pursuers in this action are a French company, ITP SA ("ITP"). The defenders, Coflexip Stena Offshore Limited ("CSO"), have places of business in Scotland. The action relates to European Patent No. EP O 890 056 B1 ("the patent"). ITP filed an application for the patent, in which the inventor was identified as Ludovic Villatte, with the European Patent Office on 28 March 1997 and it was granted on 1 March 2000, with a priority date of 29 March 1996. It was validated in the United Kingdom on 22 March 2000. It is a European Patent (UK) for the purposes of the Patents Act 1977 ("the 1977 Act").
 The patent relates, in general terms, to a heat insulated pipe-in-pipe assembly for use in pipelines to be laid on the seabed for the purpose of transporting oil products. The insulation takes the form of microporous insulation material at reduced pressure. CSO have manufactured in Scotland for a project known as BP Nile a pipeline which ITP allege infringes the patent. ITP conclude in this action for declarator to this effect, for interdict against CSO from infringing the patent by the doing of any of the things referred to in subsection 60(1) of the 1977 Act, and for an account of the profits made by CSO through the infringement. In a counterclaim, CSO seek revocation of the patent as being invalid by reason of lack of novelty and obviousness. By agreement of the parties, and in terms of an interlocutor dated 15 February 2002, the proof which I heard was restricted to what I shall call the validity issue and the infringement issue. Although ITP led at the proof, and have the burden of proof on the infringement issue, the burden of proof on the validity issue is on CSO and in due course I shall consider this first.
The statutory provisions
 By section 1(1) of the 1977 Act a patent may be granted only for an invention in respect of which certain conditions are satisfied, the first two of which are that (a) the invention is new and (b) it involves an inventive step, and references in the Act to a patentable invention are to be construed accordingly. Section 2 provides inter alia:
"(1) An invention shall be taken to be new if it does not form part of the state of the art.
(2) The state of the art in the case of an invention shall be taken to comprise all matter (whether a product, a process, information about either, or anything else) which has at any time before the priority date of that invention been made available to the public (whether in the United Kingdom or elsewhere) by written or oral description, by use or in any other way."
By section 3 an invention is to be taken to involve an inventive step if it is not obvious to a person skilled in the art, having regard to any matter which forms part of the state of the art by virtue only of section 2(2).
 By section 60(1) of the Act, a person infringes a patent for an invention if, but only if, while the patent is in force, he does any of various things in the United Kingdom in relation to the invention without the consent of the proprietor of the patent. Where the invention is a product, he infringes the patent if he makes, disposes of, offers to dispose of, uses or imports the product or keeps it whether for disposal or otherwise. Section 61 sets out the remedies which may be sought in proceedings for infringement of a patent; these include those sought by ITP in this action.
 Section 72(1) of the Act provides inter alia that the Court may, on the application of any person, by order revoke a patent for an invention on certain grounds, the first of which is that the invention is not a patentable invention. By section 74, the validity of a patent may be put in issue inter alia by way of defence in proceedings for infringement of the patent under section 61.
(4) European Patents
 By section 77(1) of the 1977 Act a European patent (UK) is inter alia to be treated for the purposes of Parts I and III of the Act as if it were a patent under the Act granted in pursuance of an application made under the Act. The provisions referred to above are in Part I of the Act, so in considering the validity issue and the infringement issue I must treat the patent as if it were one under the 1977 Act.
(5) Construction of patents
 Section 125, which is in Part III of the 1977 Act, provides inter alia:
"(1) For the purposes of this Act an invention for a patent …. for which a patent has been granted shall, unless the context otherwise requires, be taken to be that specified in a claim of the specification of the …. patent …. as interpreted by the description and any drawings contained in that specification, and the extent of the protection conferred by a patent ….. shall be determined accordingly.
(3) The Protocol on the Interpretation of Article 69 of the European Patent Convention (which Article contains a provision corresponding to subsection (1) above) shall, as for the time being in force, apply for the purposes of subsection (1) above as it applies for the purposes of that Article."
The Protocol provides:
"Article 69 should not be interpreted in the sense that the extent of the protection conferred by a European patent is to be understood as that defined by the strict, literal meaning of the wording used in the claims, the description and drawings being employed only for the purpose of resolving an ambiguity found in the claims. Neither should it be interpreted in the sense that the claims serve only as a guideline and that the actual protection conferred may extend to what, from a consideration of the description and drawings by a person skilled in the art, the patentee has contemplated. On the contrary, it is to be interpreted as defining a position between these extremes which combines a fair protection for the patentee with a reasonable degree of certainty for third parties."
The effect of these provisions, and of the cases to which I refer below, is that patents require to be given a purposive construction. This applies not only to the patent in suit, for purposes of both the validity and the infringement issues, but also to any patent forming part of the relevant prior art.
Proceedings before the European Patent Office
 Following the grant of the patent on 1 March 2000, CSO gave notification of opposition to it as lacking novelty or an inventive step in terms of Articles 52(1), 54 and 56 of the European Patent Convention. After sundry procedure, on 4 July 2002 the Opposition Division of the European Patent Office rejected the opposition. CSO thereafter filed an appeal against this decision to the Board of Appeal of the European Patent Office. By the conclusion of the hearing on evidence before me no date had yet been fixed for the hearing of the appeal, but it was expected to be in late 2003. For various procedural reasons, the Opposition Division considered fewer documents relating to the state of the art than were discussed in the evidence before me. Perhaps of most significance is that they did not consider the Pogorski patent, which I discuss below at  and  to  in relation to the alleged lack of novelty of the patent. In their statement of appeal CSO seek consideration by the Board of Appeal of documents which were not considered by the Opposition Division, in addition to those which were. As I understand it, all these documents were discussed in the evidence before me.
 A few days before the proof was due to start a motion came before me at the instance of ITP for discharge of the diet of proof and for the action to be sisted pending the decision of the Board of Appeal. This motion was opposed by CSO. After hearing counsel, I refused it. The reasons which I gave at the time were as follows. Whatever may be the powers of the European Patent Office, this Court has jurisdiction, under the 1977 Act, to determine the validity issue, so far as the validity of the patent within the United Kingdom is concerned. In any event, this Court has sole jurisdiction to determine the infringement issue. Accordingly, even if CSO’s appeal were unsuccessful, and the Board of Appeal upheld the validity of the patent, this action would still require to proceed on the infringement issue, and it would still be open to CSO to insist on the validity issue in this Court . As Dillon L.J. said in Pall Corporation v Commercial Hydraulics (Bedford) Ltd (No.2)  R.P.C.703 at p.710, successful opposition proceedings in the European Patent Office put an end to the patent; unsuccessful opposition proceedings do not prevent the issue of validity being challenged afresh in proceedings in the national courts. If the action were sisted meantime there would be a considerable delay. Whatever view ITP may take of their position, this would have important commercial consequences for CSO, who are entitled to have their legal position established without undue delay.
 In Amersham International plc v Corning Ltd  R.P.C.53 the defendants sought a stay of High Court proceedings pending determination of opposition proceedings in the European Patent Office. Falconer J said at p.58, as part of his reasoning for rejecting the application:
"… it seems to me reasonable to infer … that the intention behind the relevant provisions of the European Patent Convention is that revocation of a European patent should primarily be a matter for the national court of the designated state and that when validity is put in issue in proceedings for infringement of a European patent, which can only be brought in the appropriate court of the designated state, the intention is that both infringement and validity should be litigated in that court."
This decision and similar decisions at first instance were approved by the Court of Appeal in Buehler AG v Chronos Richardson Ltd  R.P.C.609 at pp.618-9. My view of the matter is therefore consistent with that of the English courts.
 I should add that, at least in the circumstances of the present case, I do not regard the rejection of CSO’s opposition by the Opposition Division as having any evidential significance. It was accepted that on the validity issue the burden of proof is on CSO, and I do not regard the burden as being heavier because CSO have, so far at least, been unsuccessful in the European Patent Office. I do not accept a submission for ITP that this Court would need cogent reasons to reach a different decision from that of the European Patent Office. As was pointed out by Aldous L.J. in Buehler at p.616-7, opposition proceedings are not inter partes proceedings, and a decision of the Opposition Division is not a final judicial decision as to the validity of a patent. "Once granted, the patent becomes a patent of the chosen Contracting State. It is the courts of that Contracting State that have to decide infringement and revocation and any decision of the European Patent Office does not preclude the Courts of the Contracting State from deciding all issues of infringement and revocation." This being so, in my opinion my task is to decide the issues on the evidence and the arguments which were presented to me in accordance with the usual standard of proof on the balance of probabilities.
 Two witnesses, Ludovic Villatte and John Hughes, were called for ITP, and four, Dr Ulrich Heinemann, Gordon Tough, Professor Andrew Palmer and Thomas Eyhorn, were called for CSO.
 Mr Villatte was the engineering manager of ITP. He joined the company in 1993 as a project engineer and held the posts of development engineer and project manager before becoming engineering manager. In common with the other witnesses whose first language was not English, he spoke fluent English, with occasional assistance from an interpreter. He was tendered as both a witness of fact and an expert witness. It was suggested on behalf of CSO that I should be hesitant to attach much weight to his evidence in relation to construction of the patent and infringement, as he was himself the inventor and his evidence was unlikely to be objective. There was an obvious danger, it was submitted, that he might give evidence as to what he intended the patent to mean, and such evidence was inadmissible: Glaverbel SA v British Coal Corporation  R.P.C.255. While I was alive to this possibility, I did not detect any tendency on his part to give such evidence (and there would certainly have been an objection if he had). He appeared to me to have a sound knowledge of the technical issues relevant to the case and some understanding of the principles applicable to patent validity and infringement. He was the witness who most closely answered the description of the notional addressee of the patent at the relevant date. In all relevant respects I found him to be credible and reliable.
 Mr Hughes had retired from the position of managing director of Microtherm International Limited, having worked from 1964 to 1998 specifically in the field of microporous insulation and having held various positions in the same group of companies, one of which was Micropore Insulation Limited ("Micropore"). He was also tendered as both a witness of fact and an expert witness. He gave evidence about the commercial relationship between Micropore and ITP which led to the development of an insulating panel for use in the ITP invention, and also gave evidence as a person skilled in the art of the manufacture, development and application of microporous insulation. He had extensive experience of patents, in some of which he was identified as the inventor. Insofar as his evidence related to the perceived advantages, disadvantages, characteristics and prior applications of microporous insulation, I found it to be of great value. He was able to explain technical matters with clarity. He gave his evidence in a careful and considered manner. While noting that he was not of course a person skilled in the art for the purposes of validity and infringement, I nevertheless found his evidence to be of assistance. It was submitted that because of his involvement with Mr Villatte in the development of the ITP invention I should treat his evidence as not wholly reliable. I do not accept this. I found him to be in all material respects both credible and reliable.
 Dr Heinemann, of the Bavarian Centre for Applied Energy Research, was a physicist with extensive qualifications and experience. He prepared a report by agreement between the parties. There was no dispute about the report or his evidence.
 Mr Tough had been a pipeline engineer employed by CSO from 1997. He gave evidence in particular about his involvement with the BP Nile project and about qualification testing carried out on insulation panels manufactured by Wacker-Chemie GmbH ("Wacker"). In one respect, which I note below, I found his evidence to be unreliable. If I had had to make findings of fact about the question of hydrogen permeation (see  and ), I would have held his evidence to be less than satisfactory.
 Professor Palmer was Jafar Research Professor of Petroleum Engineering at Cambridge University and at the time of the proof was also a visiting professor in engineering at Harvard University. Among other qualifications he was a Fellow of the Royal Society. In addition to his very extensive academic experience he had held positions in engineering companies and at the time of the proof was managing director of such a company. He had significant experience in the field of offshore pipeline engineering and was a skilled reader for the purposes of considering the issues of construction and infringement of the patent. In many respects I found him to be an impressive witness. There were however points on which he was mistaken, and I refer to these below. I also felt that at times he was inclined to overstep the function of an independent expert witness and to engage in advocacy in a manner which tended to disregard any material which might point to a different conclusion from the one he had formed. At times also he fenced with the questioner under cross- examination. Prior to the work which he carried out after being engaged as an expert witness, he had no familiarity with the field of microporous insulation. Perhaps for this reason, where the prior art lay in this field, he tended to overstate its teaching. I shall have further comments to make about his evidence in due course.
 Professor Palmer’s evidence was diametrically opposed to that of Mr Villatte and Mr Hughes on every significant issue on which expert evidence was led. As will be seen, I prefer their evidence to his. Where I make no specific comment about the evidence of individual witnesses in deciding an issue, it may be taken that I have done so on the basis of this preference.
 Finally, Mr Eyhorn, an engineer heading the research and development department of Wacker, gave evidence about Wacker microporous insulation products. There was no dispute about his evidence in this regard, and I found it to be helpful. He was also asked questions about the Fricke paper (see ), which I found to be of some assistance in understanding the paper. He was not tendered as an expert witness, and what he would regard as common general knowledge about microporous insulation was a great deal more specialised than that of the notional addressee of the patent.
The facts - background
(a) Pipe-in-pipe systems
 The increasing exploitation by oil companies of fields situated below deep sea water has given rise to specialised technological developments. Satellite wellheads may lie at depths of hundreds of metres below the surface of the sea, and at distances of tens of kilometres from host facilities such as production platforms. The oil (an expression which, without requiring to be more specific for present purposes, may be taken to apply to whatever fluid flows from a well) reaches a wellhead. It then has to be carried along the seabed in a pipeline called a tie-back to a point where it passes into a riser and travels to the host facility at the surface. The sea water at such depths may have a temperature as low at 2oC. At the wellhead the oil is hot (typically in the range 100-200oC). Its temperature requires to be maintained above a minimum of about 40oC throughout the length of the pipeline, in order to prevent the formation of paraffin wax, which occurs when the temperature falls below 40oC, and hydrates, when the temperature falls below about 20-25oC. These can make the oil too viscous to pass along the pipe and can even have the effect of blocking its flow entirely. In that event remedial measures are expensive, and in the worst case the pipeline may have to be abandoned. The risk is particularly great if the wellhead is shut down for maintenance, so that the oil in the pipeline is stationary for some hours.
 Much ingenuity has been devoted to devising means of insulating sub-sea pipelines in order to maintain the temperature of the oil. Heat loss is measured by reference to the overall heat transfer coefficient ("OHTC") of the system, usually expressed in terms of W/m2K. There is a steady demand from oil companies for a reduction in the OHTC of pipeline systems. In the early 1980s (or perhaps as early as the late 1970s - the evidence on this was not entirely clear) pipe-in-pipe systems were first introduced. In such a system, an inner flowline is drawn during assembly through an outer carrier pipe. The external diameter of the flowline is less than the internal diameter of the carrier pipe. Annular (ring-shaped) spacers are used at intervals to separate the flowline from the carrier pipe. The spacers bear the weight of the flowline. In the final assembly the pipes are axially concentric. The space between them is referred to as the annulus. I am principally concerned with the means which have been devised of reducing to an acceptable level the transfer of heat from the flowline, which may be taken to be at the temperature of the oil within it, and the carrier pipe, which may be taken to be at the temperature of the surrounding sea water.
 Typically, a pipe-in-pipe system is assembled in straight lengths. I am not concerned with how these lengths are joined together to form the pipeline. It will, however, help to understand some later passages if I mention that one method involves the onshore assembly of lengths of up to 1,000 metres, referred to as stalks. The stalks are then joined together and spooled or coiled on to the reel of a reelship, from which they are subsequently laid, being straightened in the process. The service life of any pipe-in-pipe system may be from 12 to 25 or even 30 years.
(b) Microporous insulation
 Heat may be transferred from a heat source through thermal insulation by solid conduction, by infra-red radiation transmission, by gaseous convection and by gaseous molecular conduction. I am principally concerned with the fourth of these. Various measures may be taken to reduce heat transfer by any of these processes. The insulating material may take the form of particles or fibres, between which there is minimal contact, thus reducing conduction through the insulating material. Infra-red radiation transmission can be reduced by various measures, one of which is the inclusion within the insulating material of opacifiers of various types, which reflect, absorb or scatter infra-red radiation. Gaseous convection is prevented when the spaces between the particles or fibres of the insulating material - known as cells - are too small for convection currents to be set up. In the absence of convection currents there is still air.
 Gaseous molecular conduction is the transfer of energy by collisions between gas molecules in the air (which is of course composed of various gases). The higher the temperature of a gas molecule, the more energy it has, and the more it moves. When it collides with another molecule it transfers to it some of its energy. By a series of such collisions heat is transferred away from the heat source, which provides the energy, through the air. In a pipe-in-pipe system, heat is thus transferred from the flowline to the carrier pipe. According to the kinetic theory of gases, the thermal conductivity of a gas is independent of pressure at moderate densities. A decrease in pressure causes a proportional decrease in the number of molecules which effect the transfer of energy, but at the same time there is an increase in the mean free path, i.e. the average distance travelled by a molecule between two successive collisions. Thus the effective rate of molecular energy exchange remains unaltered. (See, for example, Gröber & Erk, Fundamentals of Heat Transfer, 3rd edn. (1961), p.150). When, however, the pressure is decreased sufficiently, the mean free path may become of the same order as or less than the distance separating the two surfaces which exchange heat by conduction in the gas. When the mean free path of the gas molecules is greater than the dimensions of the pores in the insulating material, there is interference with gaseous molecular conduction, which is thereby significantly reduced. It thus follows from the application of the kinetic theory of gases that there is a correlation between the sizes of the pores in the insulating material and the pressure of the air in them. The smaller the pore size, the less evacuation is required to interfere with gaseous molecular conduction.
 The word "vacuum" may be used loosely to refer to any pressure below atmospheric pressure, i.e. about 1,000 mbar. The principal significance of atmospheric pressure is that in the absence of measures to alter it, this is the pressure of the air in which structures are assembled at sea level. It was, as I understood it, despite some disagreement in the pleadings, generally agreed by the witnesses that a partial vacuum in the range from 1,000 to 1 mbar would properly be referred to as reduced pressure, and that a pressure below 1 mbar would be referred to as high vacuum. By comparison with reduced pressure, high vacuum is difficult to achieve. With many insulating materials, a high vacuum is required before the mean free path of the air molecules becomes greater than that of the cells in the material.
 In about 1967 microporous thermal insulation was introduced to the market. The principal element in such insulation is silica in various compounds. These compounds are formed into particles. These particles are very fine, and can be compacted, with the addition of opacifiers and of a small proportion of fibres to add mechanical strength, to a consistency in which the material can then be put to various practical uses. The feature which distinguishes microporous thermal insulation from all other forms of thermal insulation is that the dimensions of the cells within it are less than the mean free path of air molecules at normal (atmospheric) temperature and pressure, that is to say they are less than 0.1 micron (m m). This effect is commonly referred to as the microporous principle or the microporous effect. Microporous insulation material is described as open-pore, that is to say the pores communicate with each other and with the exterior, by contrast with closed-pore materials such as polyurethane foam.
 Two companies which are regarded as leaders in the field of microporous thermal insulation are Micropore, which trades under the name Microtherm, and Wacker, whose material is called Wacker WDS. Both companies have patented products which use microporous thermal insulation to exploit the microporous principle. The essential feature of such products is that the thermal conductivity of the air in the cells of the insulating material is less than that of still air at normal temperature and pressure.
 Various brochures and product lists available before the priority date of the patent show that products incorporating microporous thermal insulation were available in a number of forms for a wide range of applications. These included products suitable for insulating pipes, such as moulded sections or half-shells, and also flexible products which could be wrapped around pipes. Such pipe insulation was sold for use at a surface temperature of 900 or 950oC.
 Microporous insulation was not used at reduced pressure in any application before the priority date of the patent. This may be accounted for by the fact that the microporous effect occurs at atmospheric pressure. There is, however, a significant improvement in the performance of microporous insulation at reduced pressure. At a pressure of 700 mbar, which is most relevant for present purposes, it was agreed that there is an improvement of 25% compared with the performance at a pressure of 1,000 mbar. There was evidence that at 100 mbar the improvement is in the region of 50-70%, and at 10 mbar 80%.
The origins of the patent
 ITP are a small company, with a staff of about twelve, incorporated in about 1991. Mr Villatte joined the company in 1993, initially as a development engineer and thereafter as project manager and subsequently engineering manager. In 1993 to 1994 he was engaged as project engineer on a project known as Total Dunbar. In this project a pipe-in-pipe system was constructed in which the insulation in the annulus took the form of fibreglass in argon at atmospheric pressure. The thermal conductivity of argon is less than that of air.
 The next ITP project in which Mr Villatte was engaged was called Shell ETAP. CSO, who are a much larger company, with about 1,000 employees, were also involved in this project. In connection with this project, Mr Villatte began to consider the possibility of using xenon in place of argon, because its thermal conductivity is even less than that of air. It is, however, considerably more expensive, so he began to consider the possibility of using it at a considerably reduced pressure. His interest in the thermal conductivity of various gases at reduced pressure and high vacuum led him to read various textbooks. In giving evidence, he did not specify what textbooks he consulted, and none of them was lodged as a production; it was suggested on behalf of CSO that I should find his evidence unreliable on this account, but I see no reason to do so. The kinetic theory of gases is set out in many textbooks and explains the performance of various insulation materials in air and other gases at various pressures.
 What ITP claim was an inventive step on Mr Villatte’s part had two aspects. First, his research led him to appreciate that at atmospheric pressure microporous insulation is very much more efficient than other types of thermal insulation. In the case of a pipe-in-pipe system, this has significant consequences. In order to obtain the same benefit as conventional forms of insulation, microporous insulation can be much thinner. This means that the width of the annulus can be greatly reduced, with the result that, for any given diameter of flowline, the diameter of the carrier pipe can be greatly reduced. In a paper prepared by Jean Marie Gueguen, the business development manager of ITP, in October 1996, with the title "A Highly Insulated Reelable Pipe-in-Pipe", figures were given for the dimensions of a carrier pipe for a flowline of 8⅝ inch diameter. For fibreglass insulation in air a carrier pipe of 16 inch diameter was required, for fibreglass insulation in argon it was 14 inches and for microporous insulation in air it was 10ľ inches. The weight of the 16 inch carrier pipe was 196 kgs per metre, for the 14 inch was 146 kgs and for the 10ľ inch was 72 kgs. There are thus obvious savings to be made by reduction of the diameter of the carrier pipe. While I was given no figures, it is obvious that there are savings in the cost of the steel, assembly, reeling, transport and laying of the pipeline. The parties proceeded before me on the basis that if a pipe-in-pipe system with open-pore microporous insulation at reduced pressure in the annulus is a patentable invention, it is of very great value.
 In the Shell ETAP project, microporous insulation was used with air at atmospheric pressure in the annulus. ITP have subsequently supplied a pipeline for a project known as Elf Tchibeli, using microporous insulation in air at reduced pressure. These pipelines comply with the oil companies’ specifications and perform satisfactorily in service.
 As a result of Mr Villatte’s realisation that microporous insulation at reduced pressure could have these advantages, ITP approached Micropore. The intention to use reduced pressure was not initially disclosed and, as I have mentioned, had not previously been put into practice. The initial reaction of Micropore was one of surprise. Microporous insulation material is expensive by comparison with other insulation materials, and for a pipeline tonnes of it would be required. It had not previously been used in any similar application. It was not immediately apparent that the savings would be greater than the increased cost of the insulation material. When the approach was reported to Mr Hughes, his initial reaction was to refer to ITP as "these mad Frenchmen". Nevertheless, Micropore were convinced of the sense of what was proposed. The requirement was to provide microporous insulation material in a product which could be wrapped round a flowline between the spacers. Mr Hughes had what he called a brainwave, and this led to the development of a product in respect of which United Kingdom Patent No. GB 2 310 273 A was granted, with priority dates 13 February 1996, 15 March 1996 and 29 March 1996. The product was described, in terms of Claim 1 thereof, as follows:
"A flexible thermal insulation panel comprising a block of consolidated particulate microporous insulation material enclosed in a porous envelope, the block being bonded to the envelope by penetration of particles of insulation material at the surface of the block into pores of the envelope, the envelope comprising a stretchable material, at least in part, to enable the consolidated block and the stretchable material of the envelope bonded thereto to be conformed to a non-planar surface with the stretchable material of the envelope remaining bonded to the block."
 In the patent as published by the European Patent Office, and produced in this action, the language of the specification was French and the claims were in French, German and English. Also produced in this action is a translation of the specification into English, which I take to be the translation filed at the Patent Office in compliance with section 77(6) of the 1977 Act. Some reference was made by witnesses at the proof to the French text of both the claims and the specification, particularly during the evidence of Mr Villatte. I understand that concurrent proceedings relating to the patent before the European Patent Office are being conducted in French. Passing reference was made at the hearing on evidence before me to the provisions of subsections (1) and (2) of section 80 of the 1977 Act, which relate to the authentic text of European patents. At the hearing on evidence, however, counsel were agreed that I should have regard only to the English version of the claims and specification, and I shall proceed on this basis.
 It is appropriate to quote the terms of the claims in full. They are as follows.
"1. A double casing pipe to be especially used in offshore oil pipelines, characterised in that, in an annular sealed space (5) located between an inner tube (1) and an outer tube (2) both coaxially arranged inside each other, there is included a self-sustaining plate (7, 8, 9) made of open pore-microporos material, which is flexible enough to be wound around the inner tube (1), and in that there is provided outside said material within said annular space, a free passageway to allow longitudinal gas flow whereby low pressure is maintained throughout said annular space.
2. A pipe according to claim 1, characterised in that said passageway is in the form of an annular layer which remains free between the plate of microporous material and the inner wall of the outer tube, said plate being inferior in thickness to said annular space (5).
3. A pipe according to claims 1 or 2, characterised in that said low pressure is comprised between 0.5 and 100 millibar.
4. A pipe according to claims 1, 2 or 3, characterised in that said microporous material is in the form of ceramic-based insulation plates arranged throughout the pipe.
5. A pipe according to claim 4, characterised in that the material of said plates consists of a mixture of silica powder and ceramic reinforcing fibbers, said combination being compacted into a coherent three dimensional structure made up of fine particles which is enclosed inside a non tight casing.
6. A pipe according to claim 5, characterised in that said casing consist of a cotton fibber tissue, preferably of a non-woven type.
7. A pipe according to anyone of claims 4 to 6, characterised in that said microporous material consists of a mixture containing a major portion of silica with a minor portion of titanium dioxide.
8. A pipe according to claim 7, characterised in that the portion of titanium dioxide present in said material is comprised between 30 an 35% by wt. for a silica content of 60 to 60% by wt., based on total weight of the composition thereof.
9. A pipe according to anyone of claims 1 to 8, characterised in that the portion of open pores in the material forming said plate is 85 to 95% based on total pore volume, with an average pore diameter less than or equal to 0.1 m m.
10. A pipe according to claim 2, when optionally combined with anyone of claims 3 to 9, characterised in that the layer which is left free along said outer tube (2) by the plate of microporous material has an average thickness ranging from 0.5 to 5 mm.
11. A pipe according to anyone of claims 1 to 10, characterised in that it comprises centering spacers between said inner tube (1) and said outer tube (2), regularly arranged in tight fit on said inner tube (1) throughout the pipe, which form reinforcing elements and longitudinal thrust-blocks for individual plates of said microporous material.
12. A pipe according to anyone of claims 1 to 11, characterised in that it includes a foil (13) for protecting said plate (7, 8, 9) which is circumferentially applied around said plate and which, preferably, has a low surface friction factor.
13. A pipe according to claim 12, characterised in that said foil (13) is made of shrink material that promotes mechanical vibration coupling of said plate to said inner tube.
14. A pipe according to anyone of claims 1 to 13, characterised in that it includes at least one anti-radiant foil, interposed between said inner tube (1) and said outer tube (2) and co-acting with said plate (7, 8, 9) of microporous material and low pressure free passageway.
15. A pipe according to anyone of claims 1 to 14, characterised in that said outer tube is a steel tube which is fitted externally along an also steel inner tube, previously provided with said plate of microporous material, the annular space being subsequently hermetically sealed at both ends of the pipe by means of an in-between ferrule located between said coaxial tubes.
16. A method for using a pipe according to anyone of claims 1 to 5, characterised in that during the service lifetime of a pipeline made from said pipe, the pressure generated within said annular space is varied between values up to 50 bar and values in the range of 1 mbar to 900 mbar, in order to vary the outward overall heat transfer coefficient of said pipe in the range of 0.5 W/m2oC to 5 W/m2oC, the thickness of said plate of microporous material being chosen to lie in the range of 10 to 14 mm, and a longitudinal gas flow layer according to claim 2 is provided with a mean thickness in the range of 1 to 5 mm."
The original version of the foregoing text and the passages quoted below contains some obvious typographical errors, which I have not seen fit to correct.
 According to the specification, page 10, line 27, the drawing in figure 1 represents an embodiment example. The figure is explained thus:
"This figure is a longitudinal partial cross section of a double casing pipe according to the invention, which hence comprises an inner tube 1 coaxially fitted inside an outer tube 2, in the form of a prefabricated item delivered from a production facility to be transported to the installation site where identical pipes are sequentially joined end to end to form a submarine pipeline.
There is schematically outlined a sleeve 3 which is additionally mounted at the joint portion between two pipes welded endwise along their respective inner tubes 1.
There is also shown an intervening ferrule 4, positioned at both ends of the tube which defines a sealed annular space 5 therebetween comprised between two individual tubes.
This ferrule of a substantially conical shape, which forms a so-called terminal hub as known in the art, is hermetically welded at one side of the inner tube 2, so as to leave a sufficiently large portion thereof exposed to archieve a welded connection 6, as well as terminally from within behind the outer tube 2.
Referring to the same figure, there are shown plates of microporous material 7, 8, 9 which are circumferentially wound on inner tube 1 and dimensioned in order that opposite edges join along a generating line of said tube, as well as straps or collars 11, merely consisting of self-adhesive paper strips, to bond adjacent edges together in intimate contact with the outer wall of the outer tube 1.
Also shown, in a lengthwise arrangement along the pipe are plates 7, 8 and 9 spaced apart by spacers 12 being interposed therebetween. These consist of half-shells securely fixed together and firmly applied on inner tube 1. These shells mainly consist of a cast organic material. The outer diameter thereof is inferior to the inner diameter of outer tube 2, so as not to interfere when fitting tubes 1 and 2 inside each other irrespective of variations in wall thickness and roundness which are usually tolerated during manufacture of such tubes.
Spacers 12 thus obtained have both a crosswise centering function of tube 1 inside outer tube 2 and a locking function between successive plates of microporous material along a longitudinal direction. These plates further constitute mechanical reinforcing elements directly transmitting to the inner tube rather via insulating plates bending strain applied on the pipe during offshore installations.
In the embodiment example set forth herein, the microporous material is comprised of a heat insulating plate based on pyrogenated silica gel being enclosed within a cotton tissue casing.
More specifically, reference is made to a plate produced by Micropore International Ltd. Company under tradename Microtherm, wherein a silica-based microporous structure contains approximately 65% of silica and about 32% of titanium dioxide, the balance of the composition being comprised on a weight basis of alumina and trace contents of different other metal or alcali-earth metal oxides, essentially derived from alumina silicates of which silica particle crosslinking fibbers are composed.
Referring again to that particular example, the thickness of the microporous plate fills one half of the annular space 5 located between the two coaxial tubes.
For a thickness of 15 mm and an annual space of 30 mm around inner tube 1 of a typical thickness (13 mm) to match a fluid passageway section of 430 mm in diameter, a comparable thickness of a air volume is maintained free nearby outer tube 2."
Figure 1 is reproduced below.
 Although a number of other passages in the specification were referred to in evidence, only two passages were ultimately treated as being of importance at the hearing on evidence. In a paragraph on page 2, lines 22 to 33, the invention is outlined in these terms:
"In order to cut expenses and improve the standard and durability of heat insulation, there is provided according to the invention a pipe with a heat insulating double casing, which is characterised in that, within a sealed annular space lying between an inner tube and an outer tube being coaxially arranged inside each other, it comprises a self-sustaining plate of an open pore-microporous material, which is flexible enough to be circumferentially wound along the inner tube, and in that there is provided outside said material in said annular space, a free passageway for longitudinal gas flow enabling low pressure to be maintained throughout said annular space."
I have omitted from this quotation an accidental duplication of the last two lines as printed. It can be seen that the wording of this passage is similar, but not identical, to that of Claim 1. In a paragraph on page 5, lines 27 to 36, it is stated:
"A striking feature of the invention is that the space occupied by the microporous material within the annular space between the two coaxial tubes maintains a free passageway for laminar air flow thus promoting suction and generating reduced pressure from on section to another through the entire pipe as applied from one end thereof. Furthermore, the seal requirements become as a result less stringent, thereby simplifying production and transport operations pipes undergo to the pipeline installation site and resulting moreover in cost savings."
 A United States Patent No. 6,145,547, dated 14 November 2000, in which Mr Villatte is identified as the inventor, has also been granted in respect of the same invention. In their pleadings CSO point to some differences of language between the two patents, but this was not referred to at the proof. My task is to construe the English version of the patent in suit as at its priority date, in accordance with well-recognised principles.
The validity issue: lack of novelty
 CSO aver in their pleadings that the invention in respect of which the patent was granted lacks novelty within the meaning of section 2 of the 1977 Act because it formed part of the state of the art at the priority date of the patent, i.e. 29 March 1996. They aver that it is wholly anticipated by United Kingdom Patent No. 1 210 275 for thermal insulation and a thermally insulating device, the application for which was filed on 8 October 1968 by Gulf Oil Canada Limited and another and in which Louis Pogorski is identified as the inventor ("Pogorski").
 The test for lack of novelty can be taken from the following cases. In Hills v Evans (1862) 31 L.J. Ch.457 the Lord Chancellor, Lord Westbury, (who heard the case at first instance) said at p.463:
"Now the question is, what must be the nature of the antecedent statement? I apprehend the principle is correctly thus expressed: the antecedent statement must be such that a person of ordinary knowledge of the subject would at once perceive, understand, and be able practically to apply the discovery without the necessity of making further experiments and gaining further information before the invention can be made useful. If something remains to be ascertained which is necessary for the useful application of the discovery, that affords sufficient room for another valid patent."
 In General Tire & Rubber Co v The Firestone Tyre & Rubber Co Ltd  R.P.C.457, Sachs L.J. discussed the concept of anticipation which arose from the provisions of the Patents Act 1949 in a passage at pages 484-6 which I have found to be of great assistance but from which I propose to quote only a few excerpts. After distinguishing anticipation by earlier use of the patentee’s device from anticipation by prior publication he said:
"If the prior inventor’s publication contains a clear description of, or clear instructions to do or make, something that would infringe the patentee’s claim if carried out after the grant of the patentee’s patent, the patentee’s claim will be shown to lack the necessary novelty, that is to say, it will have been anticipated. … [I]f carrying out the directions contained in the prior inventor’s publication will inevitably result in something being made or done which, if the patentee’s patent were valid, would constitute an infringement of the patentee’s claim, this circumstance demonstrates that the patentee’s claim has in fact been anticipated. If, on the other hand, the prior publication contains a direction which is capable of being carried out in a manner which would infringe the patentee’s claim, but would be at least as likely to be carried out in a way which would not do so, the patentee’s claim will not have been anticipated, although it may fail on the ground of obviousness. To anticipate the patentee’s claim the prior publication must contain clear and unmistakeable directions to do what the patentee claims to have invented … A signpost, however clear, upon the road to the patentee’s invention will not suffice. The prior inventor must be clearly shown to have planted his flag at the precise destination before the patentee."
Sachs L.J. also said that each of the documents must be considered separately. "For this purpose it is not permissible to combine earlier unconnected publications to show anticipation, for, if combination of earlier unconnected publications is necessary to assemble all the elements of the invention said to have been anticipated, it follows that no one man has previously made that invention and that the combination is novel."
 In Asahi Kasei Kogyo KK’s Application  R.P.C.485 Lord Jauncey said, at page 543, of an enabling disclosure that "a person skilled in the art must be able to make the [product] from the description or use to which the public has access".
 It is not permissible to engage in "mosaicing" (see Terrell on Patents 15th edn., paras.7.12-3). Each document must be interpreted on its own in order to determine the information it contains, and it is not legitimate to piece together a number of prior documents in order to produce an anticipation of the invention. The expression is derived from Von Heyden v Neustadt (1880) 50 L.J. Ch.126, in which James L.J. said at p.128:
"We are of opinion that if it requires this mosaic of extracts, from annuals and treaties spread over a series of years, to prove the defendants’ contention, that contention stands thereby self-condemned … And even if it could be shown that a patentee made his discovery of a consecutive process by studying, collating and applying a number of facts discriminated in the pages of such works, his diligent study of such works would as much entitle him to the character of an inventor as the diligent study of the works of nature would do."
 In Lowndes’ Patent (1928) 45 R.P.C.48, Tomlin J. said at p.57:
"It is not open to you to take a packet of prior documents and … by … putting a puzzle together produce what you say is a disclosure in the nature of a combination of the various elements which have been contained in the prior documents. I think it is necessary to point to a clear and specific disclosure of something which is said to be like the patentee’s invention."
 In the section of his report headed "Novelty" Professor Palmer concluded by expressing the opinion that the claims of the patent were anticipated by Hughes
(see ) "with the addition of a free passageway along the length of the pipe, which is well known", and also by Kerspe (see [77-8]), "with the replacement of one material by another", and that they were also anticipated fully by Pogorski. He accepted, however, in cross-examination that mosaicing is not permissible, and at the hearing on evidence counsel for CSO expressly stated that Professor Palmer’s references to Hughes and Kerspe represented a mistaken approach to the question of anticipation. What I have to consider therefore is whether, as counsel argued, the ITP patent is wholly anticipated by Pogorski, bearing in mind the approach set out in the above cases.
 On the basis of Professor Palmer’s evidence, counsel for CSO prepared a skeleton analysis of how Pogorski anticipates Claim 1 of the patent. Various passages were said to show anticipation of (1) a double casing pipe for use in offshore pipelines, (2) an inner tube and an outer tube, (3) a self-sustaining plate of open-pore microporous material, (4) flexible enough to be wound around the inner tube, (5) a longitudinal free passageway to allow gas flow whereby low pressure is maintained throughout the annular space, and (6) the use of low pressure (partial vacuum). Although I shall refer to some of the other features, I propose to concentrate on the question whether there is anticipation of the use of microporous material and, if so, its use at reduced pressure.
 At page 1, lines 14 to 29 of the specification, Pogorski states:
"This invention relates to an improved type of thermally efficient, easy-to-apply, thermal insulation capable of supporting compressive loads and having a high resistance to all modes of heat transfer over a wide range of operating conditions. More particularly, this invention relates to an improved type of thermally efficient, load-supporting, thermal insulation for cryogenic, intermediate and high temperature service having a high resistance to all modes of heat transfer when placed in an environment containing gases at sub-atmospheric to atmospheric and above atmospheric pressures. This invention also relates to thermally insulating devices using such thermal insulation."
 After this passage there is a discussion of the main function of thermal insulation and of the characteristics and limitations of various types of typical thermal insulating systems. Under the heading "Conventional powder or fiber types of insulation" the following passage appears on page 3, line 93 to page 4, line 2:
"Powders or powder mixes opaque to thermal radiation are effective in decreasing the portion of heat leak attributable to this mode of heat transfer. The contribution of residual solid conduction and radiation being small, the theoretical limits of the thermal insulating capability of powders approach, and, when certain requirements are met, surpass the insulating properties of the interstitial gas. These requirements, which are predictable from the Kinetic theory of gases, indicate that the thermal conductivity of the solid gas system may be lower than the thermal conductivity of the interstitial gas at given temperature and pressure conditions when the dimensions of the gaps between the loosely-packed solids are comparable to or lower than the molecular free path in the gas phase.
The required conditions can be met by decreasing the interstitial gas pressure, and thus increasing the length of the molecular free path, by decreasing the particle size or by decreasing both. By employing these techniques, the conductivity of powder or loose fiber-filled thermal insulating systems can be decreased to a point where radiation and residual solid conduction through the point contacts will become dominant over convection [sic]. The thermal conductivities of properly formulated, evacuated powder or fiber mixes can reach an efficient low of 0.01 to 0.002 Btu inch/hr ft2 oF at moderately mild vacuums (10-1 to 10-2 - 10-4 Torr)."
One Torr is approximately 1.3 mbar.
 After discussion of the various types of typical thermal insulating systems, the specification continues at page 4, lines 31 to 83:
"The foregoing discussion of the prior art indicates that previous types of efficient thermal insulations have one or more undesirable characteristics, e.g. inability to support heavy loads, high vacuum requirements, and limited operating temperature range. Inability to support loads creates the necessity for relatively highly conductive solid supports which, apart from mechanical complications in the vessel structure and construction, increase the practical effective overall conductivity of the insulated system much above the theoretical values. High vacuums are difficult and costly to obtain and maintain, while a limited service temperature range narrows the applications of an insulation. Any of these factors is serious enough to considerably affect or limit the usefulness of such previous types of insulations.
In accordance with one aspect of the present invention, there is provided thermal insulation capable of supporting a load, comprising a flexible casing filled with compacted material, said compacted material exerting a pressure over the whole inner surface of said casing of at least one pound per square inch and being in the form of finally divided particles, said compacted material having a coefficient of thermal conductivity less than that of the interstitial gas between said particles under the same conditions of temperature and pressure.
The thermal insulation can be used in high vacuum environments, is capable of withstanding mechanical vibrations, and, depending upon the materials chosen, can be used over a wide temperature range.
According to another aspect of the present invention, there is provided a thermally insulating device having an inner wall, an outer wall and thermal insulation according to the first aspect disposed between the walls. The insulation may be the sole supporting member contacting both walls and extending between both walls, or may contact one of the walls and another supporting member which contacts the other wall but not the said one
The casing may be gas permeable or impermeable, and the insulator may be in the form of a tube, a quilted blanket or a cushion, for example. The particles may be fibers, powders or fiber-powder mixes."
 Reference is then made to six figures. Figure 1 is a sectional view through a typical, prior art, powder-in-vacuum, thermally insulated double wall container; figure 2 is a sectional view similar to figure 1 but showing a thermally insulated device embodying the present invention; figure 3 is a sectional view along a line shown in figure 2; figure 4 is a view similar to figure 2 showing a part of the container thereof in greater detail than in figure 2; figure 5 is a perspective view of a roll of tubular type thermal insulation embodying the invention; and figure 6 is a perspective view of a quilted blanket type thermal insulator embodying the invention. Of figure 2, it is stated at page 5, lines 22 to 30:
"Although the container shown is like that of Figure 1 and may be used, for example, for the storage of liquid oxygen, it will be appreciated that the invention is applicable to the insulation of any device that requires thermal insulation and is particularly suited for use with double wall containers or conduits such as pipe lines, for example."
At page 5, lines 52 to 60 there is a statement that the use of a gas permeable casing is particularly advantageous where the thermal insulation is to operate under partially evacuated conditions, since the permeability of the casing permits gas to be evacuated from within the casing after the casing has been placed in situ.
 In a passage on page 5, lines 74 to 88, it is stated that the compacted material consists of finely divided particles, which may be powders, fibres or mixtures of powders and fibres. A wide variety of particulate material can be employed. It may be quartz or glass fibres, aluminium powders (opaque to thermal radiation) or mixtures of fly ash with expanded silica, to name only a few possibilities. On page 5, lines 89 to 94, it is stated:
"The size of the particles may vary widely, but, in general, will range between 10Å [Ångströms] and 2mm. It has been found that a mixture of both large and small particles gives the best result. The shape of the particles is not a critical consideration."
 An example is given of a mixture of 50% by volume of ash and 50% by volume expanded silica having a particle size of from 150Å to 0.5 microns. This was compacted into a casing to withstand a pressure of 120lbs per square inch, the casing being of fibreglass cloth. This insulation was wrapped in three one inch layers around the inner wall of a double wall, liquid nitrogen container and then placed within the outer wall. The vessel had no supports. The space between the walls was evacuated to 1 Torr (approximately 1.3mbar). Results are given for the effective overall conductivity of the insulated system after having been subjected to various tests.
 At page 7, lines 9 to 16 it is stated:
"It is to be understood that while thermal insulation embodying this invention can be placed in a partially evacuated environment, this is not essential, and it may be located in an environment of air or other gas, such as nitrogen, argon, helium, carbon dioxide and freon, at pressures ranging from sub-atmospheric to above atmospheric."
 The claims are in these terms:
"1. Thermal insulation capable of supporting a load, comprising a flexible casing filled with compacted material, said compacted material exerting a pressure over the whole inner surface of said casing of at least one pound per square inch and being in the form of finely divided particles, said compacted material having a coefficient of thermal conductivity less than that of the interstitial gas between said particles under the same conditions of temperature and pressure.
2. Thermal insulation according to Claim 1, wherein said particles are from 10Å to 2 mm in size.
3. Thermal insulation according to Claim 1 or 2, wherein said pressure is less than three hundred pounds per square inch.
4. Thermal insulation according to Claim 1, 2 or 3, wherein said casing is permeable to gases but substantially impervious to the passage of said particles therethrough.
5. Thermal insulation according to Claim 1, 2, or 3, wherein the inside of said casing is under a partial vacuum.
6. Thermal insulation substantially as hereinbefore described with reference to, and as illustrated in, Figure 5 of the accompanying drawings.
7. A thermally insulating device having an inner wall, an outer wall and a thermal insulation as claimed in any preceding claim disposed between said walls.
8. A thermally insulating device as claimed in Claim 7, wherein the thermal insulation contacts both of said walls and is the sole supporting member extending between said walls.
9. A thermally insulating device as claimed in Claim 7, wherein the thermal insulation contacts one of said walls and another supporting member disposed between said walls, and wherein said other supporting member contacts said thermal insulation and the other of said walls but not said one wall.
10. A thermally insulating device substantially as hereinbefore described with reference to, and as illustrated in, Figures 2, 3 and 4 or Figure 6 of the accompanying drawings."
 In considering the proper construction of Pogorski at its priority date, I bear in mind that offshore pipe-in-pipe systems had not yet come into use. This does not, however, appear to me to be of critical importance, as Pogorski is expressed in terms general enough to include pipe-in-pipe systems in any environment. What does appear to me to be critical is whether it teaches the use of microporous material, in which the ultimate size of the cells or voids is less than the mean free path of an air molecule at normal temperature and pressure, i.e. of the order of 0.1m m or smaller, at a pressure in the range 1 to 1000 mbar. Contrary to the opinion of Professor Palmer, I am satisfied that Pogorski does not teach at all, and in any event does not contain clear and unmistakeable directions in the General Tire sense, how to use microporous materials at such pressures.
 The main defect in Professor Palmer’s approach appears to me to be that he said that the reference at page 3, line 103 to the kinetic theory of gases can only be a reference to the microporous effect. This appears to me to be wrong. The kinetic theory of gases can be used to explain the thermal conductivity of gases in any insulating material at any pressure. This is recognised in the paragraph following the reference to the kinetic theory of gases, at page 3, line 112 to page 4, line 2. The particles in microporous insulating material are no doubt within the range from 10Å to 2mm in size, but a mixture of particles in that wide range would not constitute microporous insulating material. Claim 2, either read on its own or together with page 5 of the specification, lines 89 to 94, clearly contemplates the use of a mixture of particles, both large and small, within that range. Such a mixture of particles is not microporous insulating material, nor is it capable of producing the microporous effect throughout the pressure range from 1000 mbar downwards.
 In my opinion, on a proper construction of Pogorski at its priority date, the purpose of the invention was to provide a better way to store liquid gas, and in particular to avoid thermal conduction through the struts between the inner and outer walls of the container by using load-bearing insulation, achieved by compacting particulate material in a casing so as to exert a mechanical pressure outwards.
 Having regard to what may be no more than a misunderstanding between Professor Palmer and Mr Hughes, I should add that in my opinion the "said pressure" in claim 3 is a reference to "pressure" in claim 1 where it first appears, i.e. the pressure exerted by the compacted material over the inner surface of the casing, and not the pressure of the air or other gas. This latter pressure features in claim 5, which contemplates that the inside of the casing may be under a partial vacuum, an expression which is not clearly explained in the specification but which may mean a pressure below 1Torr (approximately 1.3 mbar). This would be consistent with the use of a mixture of particles in the range given in claim 2. The skilled addressee would understand from the reference to the kinetic theory of gases and from the example given in the specification that no benefit would be obtained from a reduction in the gas pressure to less than about 1 mbar. The load-bearing capacity of the claimed invention also points away from anticipation of the use of microporous insulating material because such material is not load-bearing and takes the form of the self-sustaining plate referred to in claim 1 of the ITP patent.
 At best, Pogorski is a signpost to the ITP invention, but it is most unlikely to lead, without much further experiment, to the construction of an offshore pipe-in-pipe system using a self-sustaining plate of microporous insulating material at reduced pressure in the annulus.
The validity issue: obviousness
 CSO also contend that the ITP invention does not involve an inventive step, because it would have been obvious to a person skilled in the art, having regard to the prior art (see section 3 of the 1977 Act). Counsel were agreed that the correct approach is set out in Windsurfing International Inc v Tabur Marine (Great Britain) Ltd  R.P.C.59, in which Oliver L.J., in delivering the judgment of the court, formulated at pp.73-74 four steps which require to be taken in answering the question to be decided when an objection is made on the ground of obviousness, which he described as a jury question. He said:
"There are, we think, four steps which require to be taken in answering the jury question. The first is to identify the inventive concept embodied in the patent in suit. Thereafter, the Court has to assume the mantle of the normally skilled but unimaginative addressee in the art at the priority date and to impute to him what was, at that date, common general knowledge in the art in question. The third step is to identify what, if any, differences exist between the matter cited as being ‘known or used’ and the alleged invention. Finally, the Court has to ask itself whether, viewed without any knowledge of the alleged invention, those differences constitute steps which would have been obvious to the skilled man or whether they require any degree of invention."
 In Mölnlycke AB v Procter & Gamble Ltd  R.P.C.49 Sir Donald Nicholls V-C said at p.112:
"Under the statutory code … the criterion for deciding whether or not the claimed invention involves an inventive step is wholly objective. It is an objective criterion defined in statutory terms, that is to say whether the step was obvious to a person skilled in the art having regard to any matter which forms part of the state of the art ….. We do not consider that it assists to ask whether the patent discloses something sufficiently inventive to deserve the grant of a monopoly. Nor is it useful to extract from older judgments expressions such as ‘that scintilla of invention necessary to support a patent’. The statute has laid down what the criterion is to be: it is a qualitative not a quantitative test….. The Act requires the Court to make a finding of fact as to what was, at the priority date, included in the state of the art and then to find again as a fact whether, having regard to that state of the art, the alleged inventive step would be obvious to any person skilled in the art."
 The nature of the person skilled in the art was discussed in Beloit Technologies Inc v Valmet Paper Machinery Inc  R.P.C.489. At p.494 Aldous L.J. said that the person skilled in the art was the notional addressee of the patent. He lacked inventive capacity, but was deemed to have the common general knowledge in the art. He was the ordinary man who might not have the advantages, such as libraries and patent departments, that some employees of large companies might have. On the same page he said:
"That question of fact [whether, having regard to the state of the art, the alleged inventive step would be obvious to a person skilled in the art] is a jury type question which inevitably requires the court and usually the witnesses to look back with knowledge of the invention. Such an advantage was not available to the inventor and therefore, when deciding the jury type question, the court must be careful not to be wise after the event. The court must put on ‘the spectacles’ of the notional skilled addressee at the priority date of the patent and, using such contemporary evidence as there may be, make sure that any conclusion reached is not the result of hindsight."
As it was put by Lawton L.J. in Jamesigns (Leeds) Ltd’s Application  R.P.C.68 at p.73, hindsight is not the mother of invention.
 In Technograph Printed Circuits Ltd v Mills & Rockley (Electronics) Ltd  R.P.C.346 Lord Reid said at p.355 that the hypothetical addressee is supposed to be incapable of a scintilla of invention and that when dealing with obviousness, unlike novelty, it is permissible to make a mosaic out of the relevant documents, but it must be a mosaic which can be put together by an unimaginative man with no inventive capacity. In the same case Lord Diplock said at p.362:
"The cross-examination of the respondents’ expert followed with customary skill the familiar ‘step by step’ course. I do not find it persuasive. Once an invention has been made it is generally possible to postulate a combination of steps by which the inventor might have arrived at the invention that he claims in his specification if he started from something that was already known. But it is only because the invention has been made and has proved successful that it is possible to postulate from what starting point and by what particular combination of steps the inventor could have arrived at his invention. It may be that taken in isolation none of the steps which it is now possible to postulate, if taken in isolation, appears to call for any inventive ingenuity. It is improbable that this reconstruction a posteriori represents the mental process by which the inventor in fact arrived at his invention, but, even if it were, inventive ingenuity lay in perceiving that the final result which it was the object of the inventor to achieve was attainable from the particular starting point and in his selection of the particular combination of steps which would lead to that result."
 In Inhale Therapeutic Systems Inc v Quadrant Healthcare plc  R.P.C.21 Laddie, J. at p.47 said:
"The notional skilled person is assumed to have read and understood the contents of the prior art. However that does not mean that all prior art will be considered equally interesting. The notional skilled person is assumed to be interested in the field of technology covered by the patent in suit, but he is not assumed to know or suspect in advance of reading it that any particular piece of prior art has the answer to a problem he faces or is relevant to it. He comes to the prior art without any preconceptions and, in particular, without any expectation that it offers him a solution to any problem he has in mind.".
There is a similar passage in the judgment of Laddie, J. in Pfizer Ltd’s Patent  F.S.R.16, para.63, which concludes:
"Caution must also be exercised where the evidence is being given by a worker who was not in the relevant field at the priority date but has tried to imagine what his reaction would have been had he been so."
 In Hallen Co v Brabantia (UK) Ltd  R.P.C.195 Slade, L.J. said at p.213:
"We do not think that the hypothetical technician must also be taken as applying his mind to the commercial consequences which might follow if the step or process in question were found in practice to achieve or assist the objective which he had in view. As Oliver L.J. said in the Windsurfing case,  R.P.C.59 at 72, ‘what has to be determined is whether what is now claimed as invention would have been obvious, not whether it would have appeared commercially worthwhile to exploit it’. We thus agree with the Judge [at first instance] that the word ‘obvious’ in section 3 is not directed to whether an advance is ‘commercially obvious’."
 In Optical Coating Laboratory Inc v Pilkington PE Ltd  R.P.C.145 Aldous J. said at p.166 that it was always important to consider why the alleged obvious step had not been suggested earlier, but evidence as to novelty, a delay of eight years (the interval in that case between a publication forming part of the prior art and the priority date of the patent in suit) and an advantage stemming from the invention carried no weight without evidence of a long-felt want or unsuccessful attempt to solve a particular problem.
 With these considerations in mind, I return to the present case. As to the first Windsurfing step, I accept the submission on behalf of CSO that the inventive concept embodied in the patent is the use of microporous insulation at reduced pressure in the annulus of a pipe-in-pipe system. It was submitted on behalf of ITP that there was another inventive concept, that of using a flexible self-sustaining plate of microporous insulation for an offshore pipe-in-pipe pipeline, which was embodied in the Microtherm product which was developed and patented for this specific use. While this appears to me to go to the general question of obviousness, it does not appear to me to be an inventive concept embodied in the patent: what matters is what the patentee is claiming as an inventive step.
 The next step is to assume the mantle of the normally skilled but unimaginative addressee in the art at the relevant date and impute to him what was, at that date, the common general knowledge in the art. The art in question is that of offshore pipeline engineering, and the notional addressee would be a pipeline engineer engaged in the design and construction of offshore pipelines, conveniently referred to as an offshore pipeline engineer. The only person falling in that category who gave evidence on the question of obviousness was Mr Villatte. Mr Tough was also an offshore pipeline engineer, but he did not start work in the field until after the priority date of the patent and in any event was not asked about the question of obviousness. Professor Palmer’s qualifications and experience were considerably more extensive than those of the notional addressee, and in relation to insulation Mr Hughes’s was more extensive. I accept, as Mr Villatte did, that the notional addressee would have experience of designing pipe-in-pipe systems, would be familiar with a wide range of insulation materials, would be aware of the properties desirable in insulation materials and would be alert to the possibility of using new or different materials from those used before. He would also have a general knowledge of thermodynamics and heat transfer.
 I am not satisfied, however, that the notional addressee would be aware of the existence of microporous insulation. At the priority date there had been no use of microporous insulation in an offshore pipeline or in any application at temperatures as low as those typically found in such pipelines. There had been no reference to it in periodicals which such a person might be expected to read. Before the research which I accept Mr Villatte carried out (though he gave no detail of it), he was not aware of the existence of the material, although ITP were interested in new approaches to insulation. Professor Palmer accepted that he first learned about the subject in preparing to give expert evidence in this case. There is thus no evidence that at the priority date of the patent any offshore engineer, let alone the notional addressee, was aware of microporous insulation. Even if he was, and turned to the brochures relating to Microtherm and Wacker products and to such publications as the Insulation Handbook, he would have found that the material was expensive by comparison with other forms of insulation, was promoted for use in high temperature applications, and while there were some products with applications for insulating pipes, they were not obviously suitable for the requirements of pipe-in-pipe systems.
 In the next place, while I accept that the notional addressee would have a general knowledge of thermodynamics and heat transfer, I am not satisfied that his general knowledge would extend to a theoretical understanding of the kinetic theory of gases. He might understand, as a practical concept, that thermal conductivity would be significantly reduced by the evacuation of gas to a high vacuum, but not that this would be achieved at a point where the mean free path of the molecules was greater than that of the pores in the material. No evidence has been put before me that the kinetic theory of gases formed part of the common general knowledge of the notional addressee at the priority date of the patent.
 Finally, on this point, I am not satisfied that the notional addressee would have been aware of the relationship between the thermal conductivity of microporous insulation and the pressure of air (or other gas) in its pores. Even in the Microtherm and Wacker brochures nothing is said about the effect of reduced pressure on the thermal conductivity of any product. Mr Hughes gave evidence that at the priority date of the patent Micropore would not have had the data to enable them to plot a graph of the relationship. Mr Eyhorn suggested that Wacker could have plotted such a graph, but none was produced and in any event nothing in the Wacker brochure would have suggested an inquiry which would have led to this. More generally, there had been no interest, before the ITP approach to Micropore, in the use of microporous insulation at reduced pressure in any application, and there had in fact been no such application.
 For these reasons I do not accept that it was part of the common general knowledge of the notional addressee that a benefit was to be obtained, by comparison with other methods of insulation, from the use of microporous insulation at reduced pressure.
 The third Windsurfing step is to identify what, if any, differences exist between the matters cited as being known or used and the invention. The essence of CSO’s case, as it was explained to me, is that the behaviour of all porous and fibrous materials under reduced pressure is explicable by the same principle, that reduction in the pressure in a gas increases the mean free path of its molecules. An understanding of the kinetic theory of gases does indeed provide a great deal of assistance to a person in search of enlightenment about the insulation performance of various materials in various conditions of pressure. But it is well understood that the microporous principle is unique to microporous insulation material in that the thermal conductivity in such material is less than that of air at normal temperature and pressure. It is also unique to microporous insulation material that a reduction in pressure below 1,000 mbar results in an improvement in the performance of the insulation throughout the range without the need to approach or achieve high vacuum. It appears to me to be a powerful criticism of Professor Palmer’s approach that, perhaps because of his lack of experience in this regard, he treated the microporous principle as part of a continuum and microporous insulation as having no characteristics which place it in a different category from other forms of insulation material, when all the evidence satisfies me that the microporous principle has unique features which have resulted in specialist research into suitable materials and the development of products and applications in which they may be put to use.
 Because of the view I have formed, I propose to be quite brief in my discussion of the prior art relied upon by counsel for CSO. In the first place, reference was made to four publications: (1) a paper entitled "The Warmth [Heat] Conduction of Pulverous Bodies and a New System of Warmth Isolation [Insulation] based thereon" given by Professor Maryan von Smoluchowski at the Second International Congress of Refrigeration at Vienna in 1910; (2) Gröber and Erk, Fundamentals of Heat Transfer, 3rd edn. (1961) (it was not suggested that this edition contained new information on this topic, it was simply the one that Professor Palmer found in the library); (3) Thermal Conductivity, ed. Tye (1969); and (4) "Materials Research for the Optimization of Thermal Insulations", a lecture presented by Jochen Fricke at the 13th European Conference on Thermo-Physical properties held in Lisbon in 1993 and published in High Temperatures - High Pressures, 1993, Vol.25. These publications demonstrate a developing understanding of the kinetic theory of gases and its application to the thermal conductivity of various materials at various pressures. A person who wished to research the relationship between the kinetic theory of gases and the thermal conductivity of various materials might well be led to read either Gröber and Erk or Tye, in each of which there is reference to von Smoluchowski, and he would understand from a consideration of the text and the graphs that there are materials in which the mean free path of the molecules of the air in the pores is less than that of the pore size, so that the thermal conductivity of the material is less than that of air at normal temperature and pressure. I doubt whether anyone but a specialist would have been led to read the Fricke paper. It relates to a very specialised field of current research into certain aerogel materials, particularly a monolithic silica aerogel. Such materials were not widely available at the priority date of the patent. I have no reason to suppose that the notional addressee of the patent would be aware of the existence of microporous insulation materials, let alone monolithic aerogels, or of their potential application as insulation materials in offshore pipelines. Mr Hughes’s evidence was that the information in Fricke would be of little use in helping the notional addressee of the patent to apply microporous insulations to pipe-in-pipe systems.
 In my opinion, on the evidence, while an imaginative offshore pipeline engineer, such as Mr Villatte, engaged in what would, by the standards of such engineers, be regarded as original research, might well come upon the textbooks at least, the unimaginative notional addressee would not. I am far from being satisfied that the notional addressee would, as Professor Palmer claimed, have been interested in these publications, still less that he would have drawn conclusions from them which would have led him to the claimed invention. This would particularly have been so in the absence of any product supplied for use in a comparable application, or in any application at reduced pressure.
 Another approach to the issue of obviousness advanced on behalf of CSO was to view the claimed invention as nothing more than a well-known insulated pipe-in-pipe system with microporous materials substituted for previously-used alternatives, in circumstances where the substitution was obvious. Reference was made in this regard to three patents. The first of these was European Patent No. 0 484 491 B1 with the priority date 28 May 1991, in which the inventor is named as Jobst-Hinrich Kerspe ("Kerspe"). Claim 1 of this patent reads:
"A pipeline for the conveyance of gaseous or liquid media whose temperature differs from the ambient temperature, comprising an outer pipe jacket and a radially spaced medium-carrying pipe arranged in the interior of said outer pipe jacket and encased by a thermal insulation means, with said medium-carrying pipe, in being axially biased at relatively spaced specified locations, taking support upon said outer pipe jacket serving as an abutment, characterized in that said thermal insulation means (3) is comprised of formed structures capable of withstanding compressive loads and fabricated from microglass fiber or micromineral fiber, their resistance to compressive loads being such that said formed structures maintain said medium-carrying pipe (1) in a spaced relation to the inner wall of said outer pipe jacket (2) at an insulating distance, and that the outside diameter of said thermal insulation means (3) is smaller than the outside diameter of said outer pipe jacket (2), so that said medium-carrying pipe (1) is eccentrically arranged in said outer pipe jacket (2) except for short areas in the proximity of a specified location."
 Professor Palmer’s opinion was that Kerspe discloses a pipe-in-pipe system capable of being used subsea, which has an insulant partially filling the annulus and the possibility to reduce the pressure. The substitution of microporous material for mineral wool was obvious. I do not accept this. Kerspe is not concerned with microporous insulation but with microfibrous insulation. Whereas "microporous" connotes a reference to pore size, "microfibrous" connotes a reference to fibre size. Mr Hughes’s undisputed evidence was that whereas microporous insulation might contain a relatively small proportion of fibres for strengthening purposes, no known predominantly microfibrous insulation could be regarded as microporous. Secondly, Kerspe is concerned with insulation moulded in half-shell form, by contrast with the flexible, self-sustaining plate of insulation capable of being wound around the inner pipe which is a feature of the patent. Thirdly, Kerspe is concerned with the pressure range in which there is an improvement in the thermal conductivity of conventional insulation, and it can be seen from the specification that he regarded this as being in a pressure range no higher than about 3 mbar. This contrasts with the improvement in the performance of microporous insulation material at any reduced pressure below 1,000 mbar. Finally, Kerspe is not concerned specifically with offshore pipelines and their specific insulation requirements.
 The next patent referred to was European Patent No.0 547 739 A1, with a priority date 10 October 1991, and in which Mr Hughes is identified as the inventor ("Hughes"). The patent relates to a "Method of Forming an Insulating Tube". Claim 1 is in these terms:
"A method of forming an insulating tube characterised by the steps of: providing a composite tube (16) comprising an inner tube (10) and an outer tube (14) defining an annular space therebetween, the annular space containing a compressible compacted particulate microporous insulation material (12), the outer tube (14) being made of a ductile material: drawing the composite tube (16) through one or more dies (18) so as to reduce the diameter of the outer tube (14) to a predetermined diameter while the diameter of the inner tube (10) remains substantially constant and so as to further compress and compact the particulate microporous insulation material (12) and maintain it under compressive stress; and trimming the ends of the composite tube (16)."
In preparing his report, Professor Palmer was mistakenly under the impression that Hughes refers to reduced pressure within a microporous material, when it does not. The patent is to do with a method of forming an insulating tube, one example of which is a car exhaust pipe. The insulation is load bearing and does not take the form of a flexible panel or sheet. There is nothing in Hughes to suggest that it is of any relevance to the notional addressee.
 Thirdly, counsel for CSO relied on Pogorski, should I not accept the primary argument that this fully anticipates the patent in suit and renders it invalid for lack of novelty. I do not, for reasons already given, accept that Pogorski discloses the use of microporous material. Moreover, I do not accept that the substitution of microporous material for the Pogorski insulation material would have been obvious to the notional addressee.
 It seems to me to be perfectly clear from the evidence that to use microporous insulation at reduced pressure in the annulus of a pipe-in-pipe system, with benefits which included those arising from the consequent ability to make a significant reduction in the external diameter of the carrier pipe, required not only research of a kind which would not normally be undertaken by an offshore pipeline engineer at the relevant time, but also a leap of imagination which can properly be described as inventive. To answer the question posed in the fourth step of Windsurfing, viewed without any knowledge of the invention, the differences between the matters cited by CSO as being known or used and the invention would not have been obvious to the skilled man and would have required a degree of invention. The entire history of events which preceded the patent, including the need to win Mr Hughes round to the idea and the need for him to devise a new patented Microtherm product, is consistent with this. In my opinion Professor Palmer’s views in this regard can best be explained by a reliance on hindsight.
 There are secondary considerations which support the view I have reached. The question may well be asked, if the invention was so obvious, why had it occurred to no other offshore pipeline engineer before it occurred to Mr Villatte? Microporous insulation had been on the market since about 1967, pipe-in-pipe systems had been in use since 1982 or earlier, the oil industry is one in which enormous sums of money are at stake and there is constant demand from oil companies for improved insulation performance in pipelines, and yet the invention occurred to no one before it occurred to Mr Villatte.
 One of the most telling items of evidence in this regard is a document prepared by CSO in about December 1995 or January 1996 for Shell UK Exploration and Production in connection with a tender for a project known as Gannet E & F Subsea Development. The document related to previous experience of installation of pipe-in-pipe systems from the reelship "Apache". There was a section on the insulation selection for pipe-in-pipe systems. The requirement for the Gannet development was to achieve an OHTC for the pipe-in-pipe system of 0.75 W/m2K (i.e. less than for the later BP Nile project). What were described as the insulants of most interest were low density polyurethane foam and mineral fibre insulation, and a preference was expressed for the latter. No reference was made to the use of microporous insulation. I see no reason to attribute to CSO less in the way of common general knowledge than would be attributed to the notional addressee, and if the existence of microporous insulation did not form part of their common general knowledge this reinforces the view that its use, whether or not at reduced pressure, was not obvious.
 Another point that reinforces the view I have taken is that after publication of the patent it was generally treated in the industry as representing a new departure which merited publicity, hence the paper by Mr Gueguen to which I have already referred at , and the paper by Mr Tough referred to below at . This burst of publicity in publications of interest to offshore engineers contrasts with a complete absence of any relevant publication or discussion in offshore engineering circles before the relevant date.
The infringement issue: the CSO pipeline for the BP Nile project
 In 2000 CSO contracted with Coflexip Stena Offshore Inc, an associated company, to manufacture and supply a pipeline ("the Nile pipe") for use in the BP Amoco Nile Project. The Nile Field is in two blocks in the Gulf of Mexico offshore Louisiana, USA. It was being developed as a sub-sea tie-back to a tension-leg platform in another block. The water is approximately 1,000 metres deep, with a temperature at the bottom of 2oC-4oC. The design temperature of the fluid (primarily gas condensate) to be carried by the flowline was 95oC. The pipeline was laid on the seabed from a reelship in early 2001. It is over 7 km long. It takes the form of a pipe-in-pipe system, the external diameter of the carrier pipe being 10 inches and that of the flowline being 6 inches, connected to a 6 inch steel catenary riser. The overall heat transfer coefficient requirement for the pipe-in-pipe system was 1.2 W/m2K.
 Microporous insulation was selected by CSO for use in the annulus. This and other features of the pipeline were described in a paper prepared by Gordon Tough of CSO and others for presentation at the 2001 Offshore Technology Conference held in Houston, Texas, from 30 April to 3 May 2001. An editorially simplified version of the paper was published in the issue of Oil & Gas Journal dated 13 August 2001. Microporous insulation had previously been used in the Shell ETAP project, as CSO were aware, and to the extent that it may appear to be suggested by Mr Tough in his paper that microporous insulation was used for the first time for the BP Nile project, this was not a correct statement.
 At an early stage, CSO approached Micropore with a view to obtaining microporous insulation panels from them. On 9 December 1996 Mr Hughes wrote to CSO on behalf of Micropore, explaining that there were difficulties because of their existing relationship with ITP, and there was an issue of confidentiality. As I have said, commercial application of a pipe-in-pipe pipeline using microporous insulating material was first made by ITP for the purposes of the Shell ETAP project. This was the first use of that technology, although in the event the microporous insulating material was used at atmospheric rather than reduced pressure within the annulus. CSO were involved in this project. They undertook not to use confidential information disclosed to them by ITP about ITP’s technology for other purposes. ITP have brought proceedings against CSO in the French courts for alleged breach of confidence. It is not contended in this action that CSO have not complied with their undertaking. I therefore proceed on the basis that in relation to the BP Nile pipeline CSO did not exploit ITP’s confidential information.
 The microporous insulation eventually used by CSO for the BP Nile pipeline takes the form of panels developed and supplied by Wacker. These panels are the subject of (1) European Patent No. EP 0 937 939 B1, the application for which was filed on 4 February 1999 and which was granted on 2 August 2000, and (2) United States Patent No. 6,110,310, the application for which was filed on 10 February 1999 and which was granted on 29 August 2000. The insulating material is microporous fumed silica with an added infra-red opacifier, contained within a plastic envelope. Claim 1 of the European Patent is in these terms:
"Method of insulation for curved surfaces with a panel-shaped, evacuated and thermally insulating moulded element which contains pressed and possibly hardened, microporous insulating material in one or more sheathed and evacuated layers, and has a surface with a lamellar structure, the lamellae having a depth of 40 to 95% of the thickness of the moulded element, which is characterised in that the moulded element is made to fit with the surface with a lamellar structure snugly against the curved surface and is fixed and the vacuum is destroyed in at least one layer."
The panels are described in the article in the Oil & Gas Journal referred to above:
"The panels have striations or ribs cut into the inner surface of the panel. This allows them to form a cylindrical shape for pipeline application. An additional benefit is that the striations allow pipe tolerances to be compensated for and panels to be fitted over weld caps.
As stated, the material has a weak chalk-like structure and little handling strength. The packaging therefore comes vacuum sealed to provide some strength to the panels. This vacuum packaging increases the panel curvature (helps close gaps between striations), provides protection from moisture ingress, and limits the risk of particle inhalation during handling.
A further benefit of sealing the panels at a pressure less than atmospheric is that the thermal conductivity of the insulation material is reduced. This effect is not accounted for in the design because the packaging is permeable to all but the largest gas molecules and any benefit from the vacuum would be lost prior to operation of the pipeline."
 As supplied by Wacker, each of the panels was sealed with a reduced pressure inside the plastic envelope of about 300 mbar. (There was some evidence that the pressure in some at least of the panels might have been 200 mbar, but the parties proceeded on the basis that I should treat the pressure in all the panels as 300 mbar,) Mr Tough was in charge of the qualification test programme for the pipe-in-pipe components. It is a matter of agreement between the parties in their pleadings that once the pipe was in use, the high temperature of the oil flowing along the pipe would soften or melt the plastic packaging, releasing the partial vacuum within the panels, and that this process would be complete within a relatively very short time. This was recognised by Mr Tough. For example, in a document dated 15 May 2000, which was prepared for the purposes of the programme, he wrote:
"On application of each insulation panel pin holes will be made in the panel. The panels are supplied vacuum sealed as it allows greater handling strength. An additional benefit of the vacuum is that it enhances the insulation capacity of the panel, for the purposes of the testing it is necessary to release the vacuum while the pipe in pipe is being constructed. This will simulate end of life condition where vacuum will no longer exist."
 In response to an application by ITP, before the raising of the present action, under section 1 of the Administration of Justice (Scotland) Act 1972, for recovery of certain material and documents from CSO in relation to the Nile pipe which was then being manufactured by CSO, CSO gave an undertaking. They undertook inter alia that they would permit an independent expert to be present, with an independent video cameraman, on two occasions. These were: (1) prior to the departure of the pipeline from Scotland, to view and video the pipeline, including the pipes within pipes viewed in section; and (2) at the straightening trial, once straightening had occurred, to view and video the straightened pipeline sections. The spooling and unspooling processes themselves were not to be videoed. The parties agreed on the appointment of Dr Heinemann, who was asked to act in his capacity in particular as an expert in the field of thermal insulations and microporous materials. Dr Heinemann made two visits to CSO’s base at Evanton in Ross-shire, the first on 30 November 2000 and the second on 14 and 15 December 2000. On the first occasion he was accompanied by an independent cameraman, who took a video, and on each occasion he took photographs. Employees of CSO were present, particularly on the first occasion, when John Baron provided information. Thereafter Dr Heinemann prepared a report, the accuracy of which he confirmed when he was called, briefly, to give evidence.
 Dr Heinemann made findings, based on Mr Baron’s information and his own observations. He found that the construction of the pipeline took the form of a pipe-in-pipe, the inner pipe being concentrically surrounded by thermal insulation and an outer pipe. The inner pipe had a diameter of 6 inches and a wall thickness of 18.3 mm and was coated with epoxy. The outer pipe had a diameter of 10 inches and a wall thickness of 12.7 mm, with an external corrosion coating of polypropylene. In order to pull the outer pipe over the insulated inner pipe, annular spacers made of teflon were mounted on the inner pipe at intervals of 2 to 2.5 metres and the inner diameter of the outer pipe was somewhat larger than the outer diameter of each spacer, so that there was a small annular gap between the spacer and the outer pipe. The outer diameter of the spacer was somewhat larger than the outer diameter of the inner pipe together with its insulation, so that the insulation material did not hinder the process of pulling the outer pipe over the inner pipe. The pipe stalks, 800 metres or 400 metres long, were assembled from shorter sections. The water stops (each tight in one direction) were mounted within the annular space between the inner pipe and the outer pipe at intervals of approximately 400 metres in each instance. In the event of a local defect, these would prevent the pipeline from becoming entirely flooded, and only a 400 metre long section of annular space would be filled with oil or water.
 Dr Heinemann did not direct his attention to such matters as the type and quality of the stainless steel used for the pipes, or the quality of the welds or the corrosion protections. He concentrated on facts that might concern the insulation concept and its realisation, and paid special attention to the possibilities of evacuating the pipe-in-pipe construction. He used the term "evacuation" as a synonym for reduction of gas pressure, and vacuum for reduced gas pressure, compared with the ambient atmospheric gas pressure. He said in his evidence that, generally, evacuation might affect insulation behaviour.
 Dr Heinemann visited the warehouse and examined some of the Wacker insulation panels. He found that they were approximately 1 metre long by 50 cms wide and 1 to 2 cms thick in each instance. The insulating material was contained within a transparent plastic envelope, with no metal layer to reduce the permeability for water vapour. The gas pressure inside some panels was reduced, by comparison with the ambient atmospheric pressure, giving a mechanical appearance comparable to that of evacuated coffee packets. The plastic envelope of other panels appeared to have been punctured. These non-evacuated panels were less stiff than the evacuated ones. On examination of the assembled pipe stalks, Dr Heinemann found that the insulation in each consisted of two layers of bent insulation panels, fixed by adhesive tape wrapped round them. The width of the remaining annular space between the insulation and the outer pipe was about half of the thickness of the insulation. He also viewed the tie-in station, where the pipe stalks were to be joined together during spooling on the CSO reelship "Apache". There was no equipment there for evacuation of the annular space between the inner and outer pipes. As Dr Heinemann put it, no indication for an evacuation of the annular space at any stage could be found during any inspection carried out during either of his visits.
 In his evidence, Dr Heinemann said that he was familiar with the insulation material in the Wacker panels, and that it was very simple to vary its thermal conductivity, much easier than with other materials. There would be some gas permeation through the plastic envelopes. He doubted, having regard to the manner in which the water stops were handled during assembly, whether they would remain gas tight (rather than water or oil tight) for a long time, so that if the air pressure in the annular space on one side of a water stop were different from that on the other, air would be able to pass the water stop.
 I accept Dr Heinemann’s evidence in its entirety. I accept, in particular, that it can be taken from his findings that no steps were taken by CSO to reduce the air pressure in the annulus by evacuation during assembly.
 On the evidence, the pipeline was assembled with most if not all of the Wacker panels in their evacuated state. While the plastic envelopes of a relatively small number of panels might be damaged during assembly, the great majority of them would remain in an evacuated state when the annulus was sealed and the pipeline was put into service. The effect of the release of the vacuum once the pipeline was in service would be to produce equilibration in the air pressure of the air within the panels and the air in the remaining annular space. Mr Tough calculated, in a calculation prepared for the purposes of the action and dated 4 December 2001, and the parties were agreed, that this air pressure would be about 700 mbar. They were also agreed that this would enhance the insulation performance of the Wacker panels by about 25% as compared with their performance at 1,000 mbar. Mr Tough’s evidence, which I have great difficulty in accepting at face value in view of the terms of the document dated 15 May 2000, was that the defenders failed to appreciate that this would happen.
 During the course of the proof an issue was explored as to whether this pressure of 700 mbar would persist throughout the service life of the pipeline, or whether the pressure would be increased by out-gassing and hydrogen permeation. These can produce adverse effects in a high vacuum system by increasing the pressure in the system. In broad terms, out-gassing is a term applied to the release of gases from a metal surface. Compounds such as oxides, hydroxides and other corrosion products present on the surface of the metal dissociate under vacuum and release gases. Metals also contain gases in solution, and under vacuum the gases diffuse outwards into the surrounding space. Hydrogen permeation occurs when hydrogen released by corrosion processes on a metal surface migrates in molecular or atomic form through the metal, appearing as gas in the surrounding space. Various measures, which I need not discuss here, are adopted in order to prevent or minimise the adverse effects of these processes.
 Some weeks before the proof Professor Palmer produced a supplementary report about the effects of out-gassing and hydrogen permeation in pipe-in-pipe systems. He was encouraged in this by a highly speculative and potentially misleading passage in the calculation prepared by Mr Tough. This led to a late amendment to CSO’s pleadings. A substantial chapter of the evidence of each of the main witnesses was directed to the question whether these processes would have the result, over the lifetime of such a system, of increasing the original reduced pressure to or above atmospheric pressure. At the hearing on evidence, counsel for CSO expressly disclaimed any reliance on out-gassing or hydrogen permeation as affecting the pressure in the Nile pipe in service. I do not therefore require to decide whether either of these processes affects such a system to any extent, and I leave them out of account. This means I proceed on the basis that the pressure of about 700 mbar, once established, will persist for the lifetime of the system.
 Given that CSO manufactured the Nile pipe in Scotland and disposed of it for use in the Nile project, and that ITP did not consent to such manufacture and disposal, it is not in dispute that, if the Nile pipe falls within Claim 1 of the patent, CSO have infringed the patent within the terms of section 60(1)(a) of the 1977 Act. This is a question of fact, to be decided upon a proper construction of Claim 1. If on such a construction the Nile pipe falls within that claim, then CSO’s liability is absolute. It is not necessary for ITP to prove that CSO knew of the patent and intended to infringe it, or that they sought deliberately to rely on a particular benefit of ITP’s invention, since the alleged infringer’s state of mind is irrelevant: see Merrell Dow Pharmaceuticals Inc v HM Norton & Co Ltd  R.P.C.76.
 I turn at this stage to the authorities to which reference was made, in addition to section 125 of the 1977 Act and the Protocol referred to above at . The purposive approach to the construction of patent claims was explained by Lord Diplock in Catnic Components Limited v Hill & Smith Limited  R.P.C.183 at pp.242-3 in these terms:
"[A] patent specification is a unilateral statement by the patentee, in words of his own choosing, addressed to those likely to have a practical interest in the subject matter of his invention (i.e. ‘skilled in the art’), by which he informs them what he claims to be the essential features of the new product or process for which the letters patent grant him a monopoly. It is those novel features only that he claims to be essential that constitute the so-called ‘pith and marrow’ of the claim. A patent specification should be given a purposive construction rather than a purely literal one derived from applying to it the kind of meticulous verbal analysis in which lawyers are too often tempted by their training to indulge. The question in each case is: whether persons with practical knowledge and experience of the kind of work in which the invention was intended to be used, would understand that strict compliance with a particular descriptive word or phrase appearing in a claim was intended by the patentee to be an essential requirement of the invention so that any variant would fall outside the monopoly claimed, even though it could have no material effect upon the way the invention worked.
The question, of course, does not arise where the variant would in fact have a material effect upon the way the invention worked."
 In Société Nouvelle des Bennes Saphem v Edbro Ltd  R.P.C.345, Lawton L.J. said at p.360, under reference to the speech of Lord Diplock in Catnic:
"The specification has to be given a purposive construction rather than a literal one … and the following question has to be answered: whether persons with practical knowledge and experience of the kind of work in which the invention was intended to be used, would understand strict compliance with a particular descriptive word or phrase appearing in a claim was intended by the patentee to be an essential requirement of the invention so that any variant would fall outside the monopoly claimed, even though it could have no material effect on the way the invention worked."
 Hoffman, J. analysed the passage I have quoted from Catnic in Improver Corporation v Remington Consumer Products Limited  F.S.R.181 at p.189, in these terms:
"If the issue was whether a feature embodied in an alleged infringement which fell outside the primary, literal or acontextual meaning of a descriptive word or phrase in the claim (‘a variant’) was nevertheless within its language as properly interpreted, the Court should ask itself the following three questions:
(1) Does the variant have a material effect upon the way the invention works? If yes, the variant is outside the claim. If no -
(2) Would this (i.e. that the variant had no material effect) have been obvious at the date of publication of the patent to a reader skilled in the art. If no, the variant is outside the claim. If yes -
(3) Would the reader skilled in the art nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention. If yes, the variant is outside the claim.
On the other hand, a negative answer to the last question would lead to the conclusion that the patentee was intending the word or phrase to have not a literal but a figurative meaning (the figure being a form of synecdoche or metonymy) denoting a class of things which included the variant and literal meaning, the latter being perhaps the most perfect, best-known or striking example of the class."
 In Lubrizol Corp v Esso Petroleum Co Ltd  R.P.C.727 at p.742, Aldous L.J. said that in construing a patent it is not permissible to put a gloss on a claim using a statement in the specification. The claim in that case was to a product. A passage in the specification described the preferred process to be used, and was a true teaching as to how to achieve a product falling within the invention. To read the passage as defining the ambit of the claim was to read the claim as a process claim or perhaps a product by process claim. Reference may also be made to Conoco Specialty Products (Inc) v Merpro Montassa Ltd 1992 S.L.T.444. In that case, Lord Sutherland said at p.448:
"While a purposive construction is necessary, it must be borne in mind that this is intended to be a method of construction and not an excuse for not construing the claims at all."
Lord Sutherland also said:
"When construing the patent it is for the court to do so and not for any witness, however expert. On the other hand, the court in carrying out this exercise must do so from the standpoint of the addressee who is a person likely to have a practical interest in the subject matter of the invention, that is, a person ‘skilled in the art’. In order to put itself into the position of being able to carry out this exercise, the Court must receive tuition in the art and this can only come from expert witnesses."
 On the question of the construction of the claims, reference may be made to Glaverbel S.A. v British Coal Corporation  R.P.C.255, in which Peter Gibson L.J. said at p.281 that "the characterising feature of a subordinate claim is treated as also embraced by any antecedent claim to which it is appended, the subordinate claims being narrower in scope. Thus guidance may properly be obtained from a subordinate claim on the true construction of the antecedent claim to which it is appended." Evidence of the patentee as to what he intended it to mean is inadmissible: ibid., per Staughton L.J. at p.268.
 If a claim is clear as a matter of language, it cannot be cut down or expanded by reference to words in the body of the specification: J Lucas (Batteries) Limited v Gaedor Limited  R.P.C.297 per Whitford J at p.346.
 In Amersham Pharmacia Biotech AB v Amicon Limited  E.W.C.A. Civ.1042 Aldous L.J. at para.32 referred to two systems between which there was no material difference when they were carried out, in the sense that they produced the same result, but with a different mechanism. They showed different ways that could produce an equivalent result. At para.33 he said:
"I do not believe that the Protocol introduced into our law a doctrine of infringement by equivalent effect by use of a different mechanism. That may be for the future. But at the moment the task of the Court is to construe the claim as part of the whole specification."
Reference may also be made to Sara Lee Household & Body Care Ltd v Johnson Wax Ltd  E.W.C.A. Civ.1609.
 The parties were ultimately divided by only one issue on the construction of the patent. It was agreed that claim 1 is a product claim, that claims 2 to 15 are subordinate product claims, and that claim 16 is a process claim. It was agreed that the notional addressee is an engineer engaged in the design of pipelines for use offshore, i.e. an offshore pipeline engineer. Despite a dispute in the pleadings about the meaning of the phrase "low pressure" in claim 1, it came to be a matter of agreement that it meant reduced pressure in the sense in which I have already used it, i.e. pressure below 1,000 mbar. Professor Palmer identified seven features in claim 1 of the patent. These were: (1) a double casing pipe, (2) an inner tube, (3) an outer tube, (4) a self-sustaining plate of open pore-microporous material, (5) flexible enough to be wound around the inner tube, (6) a free passageway to allow gas flow, (7) whereby low pressure is maintained throughout the annular space. There was no dispute that features (1) to (6) are present in the Nile pipe. It was also not ultimately in dispute that there is low pressure, that is reduced pressure at about 700 mbar, throughout the annular space of the Nile pipe. One way of putting the matter would be that if reference were made to the embodiment example in figure 1 in the patent, disregarding features specific to joints between sections of pipe and the ends of the pipe, a cross section through the Nile pipe would be indistinguishable in any material respect from a cross section through figure 1. In both cases, the performance of the microporous insulation at a pressure of 700 mbar would be the same, i.e. 25% more efficient than its performance at 1,000 mbar.
 In the specification of the patent a method is described for the establishment of reduced pressure by suction through a hole drilled at one end of the pipe, which hole is subsequently plugged by a weld joint (page 12, lines 24 to 31). There will in that event be longitudinal gas flow in the free passageway between the microporous insulation and the carrier pipe as air is drawn out of the annular space throughout the length of the pipe. By contrast, in the Nile pipe, low pressure will have been established throughout the annulus by equilibration of air pressure following degradation of the plastic envelopes of the Wacker panels within a short time of the pipe’s coming into service. Unless the degradation took place in all panels simultaneously, there must have been some longitudinal flow of air. For example, if the degradation took place sequentially from one end of a 400 metre section of pipe between water stops, there will have been longitudinal air flow towards that end; and, having regard to Dr Heinemann’s evidence that water stops are not gas tight, there will have been a similar longitudinal air flow past a pair of water stops if the envelopes of the panels on one side degraded before those on the other. In the case of any panels of which the envelopes had been damaged during assembly and the pressure which was accordingly about 1,000 mbar, air will have been drawn out as the pressure was reduced to about 700 mbar, and some of it will have flowed longitudinally. There is, however, no empirical evidence as to what exactly happened when the Nile pipe was put into service, and in any event there is no reason to suppose that longitudinal air flow played any significant part in the establishment of reduced pressure in the annulus of the Nile pipe. The true question appears to me to be whether the means by which reduced pressure is established is of any significance.
 I return to the phrase "whereby low pressure is maintained throughout said annular space" in claim 1. Adopting the mantle of the notional skilled addressee, I am aware inter alia that in the assembly of a pipe-in-pipe system with microporous insulation in the annulus a free space requires to be left to avoid damage to the insulation when the insulated flowline is drawn through the carrier pipe. Claim 1 teaches me that there requires to be low pressure, i.e. reduced pressure of less than 1,000 mbar, throughout the annular space, and that this low pressure requires to be maintained. The Oxford English Dictionary defines "maintain", among other senses, as meaning "to keep up, preserve, cause to continue in being (a state of things, a condition or activity, etc"). I would understand therefore that maintenance of a state of things is not the same thing as its establishment. I would also understand that low pressure, once established, would be maintained by the annular space being sealed, as in the phrase "an annular sealed space".
 The word "whereby" is defined in the Oxford English dictionary, among other senses, as meaning "by means of or by the agency of which". Reference was made by counsel for CSO to Imperial Chemical Industries v Montedison (UK) Ltd  R.P.C.449. In that case the claim was for a composition comprising a stated combination of ingredients A, B and C "whereby" a certain result was achieved. In the Court of Appeal, the three members of the Court each arrived at a different construction: Stuart Smith L.J. held that C must be a causa sine qua non, Morritt L.J. held that the effect had to be obtained by the combination of all three ingredients, and Sir John May held that C should be the causa sine qua non or the dominant cause. As the question is put in Terrell on Patents, para.6.54, must an integer be the sole cause, the dominant cause, or merely a contributing cause of a given effect? It can be seen from this that the nature of the causal connection connoted by the use of the word "whereby" may depend on its exact context.
 In my opinion the context here is that of a description of a sealed system in which there is low pressure, and in which there is a free passageway for longitudinal gas flow should conditions arise in which that would contribute materially to the maintenance of low pressure throughout the system. In my opinion, on a proper construction, longitudinal gas flow, and in particular longitudinal gas flow caused by suction at one end of the pipe, is not intended to a sine qua non of the product. On a purposive construction, claim 1 describes a product which is a pipe-in-pipe system with microporous insulation at reduced pressure in the annular space. All that is required to make the product work is that there should be reduced pressure and that it persist for the service life of the pipe. In my opinion claim 1 describes a working product. It is not directed to the means by which reduced pressure is initially established, and accordingly, notwithstanding discussion in the specification of one means of establishing it, it does not in my opinion expressly or by necessary implication exclude any other means.
 It follows therefore that in my opinion the Nile pipe, having no material difference as a working product from that described in claim 1, infringes that claim. The fact that low pressure has been established by a means other than suction at one end of the pipe is of no relevance. In service, both the product as described in claim 1 and the Nile pipe have reduced pressure, which is maintained throughout the annular sealed space.
 The construction which I prefer involves rejection of a submission on behalf of CSO that, in effect, the phrase "whereby low pressure is maintained throughout said annular space" connotes a causal connection between longitudinal gas flow in the free passageway and the establishment of reduced pressure. If that submission were correct, it would be necessary to go on to consider what are usually called the Improver tests. On that hypothesis, I now consider these tests.
 So far as question 1 is concerned, the variant in the Nile pipe, i.e. the establishment of reduced pressure by equilibration following degradation of the plastic envelopes of the Wacker panels, does not have a material effect upon the way the invention works. As I have said, the invention (and this is common ground) is a pipe-in-pipe system with microporous insulation at reduced pressure in the annulus. There are two aspects to this: the use of microporous insulation, thus obtaining the benefit of the microporous effect, and the enhancement of that effect by the use of reduced pressure, which confers a significant benefit in a wide range below 1,000 mbar, including 700 mbar. How the reduced pressure is established has no material effect upon the way the invention works. This is not a case of equivalent effect, as in Amersham and Sara Lee. The invention works in exactly the same way, and there is no material effect upon the way in which it works whichever of the two means of establishing reduced pressure is employed.
 Turning to question 2, in my opinion it would have been obvious at the priority date of the patent to a reader skilled in the art that the variant, if it be one, does not have a material effect. The skilled reader would understand the teaching in the patent of the benefits of using microporous insulation at reduced pressure, and would understand the importance of establishing and maintaining reduced pressure in order to obtain these benefits; and it would have been obvious to him that the variant means of establishing reduced pressure would not have a material effect upon the way in which the invention worked and the benefit was obtained.
 Finally, the answer to the third Improver question is in my opinion that the reader skilled in the art would nevertheless not have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention. It is true that the purposive approach to construction does not allow one to ignore limitations in a claim which a skilled reader would understand to have been deliberately included to achieve a particular, stated and wanted, technical effect (see Arjo Ltd v Liko AB, Case No. HC 99 04062, 8 November 2001, per Laddie J. at para.42). But it is one thing deliberately to include restrictions in order to achieve a desired effect. It is quite another, as would be the case here, to make express reference to one convenient means of achieving a desired effect. I can find nothing in claim 1, even read together with the passages in the specification relied upon by counsel for CSO, that would in my opinion lead the skilled reader to conclude that, in the absence of any intelligible reason for doing so, the intention was to exclude any other means of achieving the desired result.
 Accordingly, even if I had to give answers to the Improver questions, they would be (1) No, (2) Yes and (3) No. The result therefore would in any event be that I would hold claim 1 to be infringed by the Nile pipe.
 For the foregoing reasons, I hold that ITP’s patent is valid and that CSO have infringed it. It was not in dispute that, should I so hold, ITP are entitled to the remedy which they seek. I shall accordingly sustain the first and second pleas-in-law for ITP on the principal action, sustain the second and third pleas-in-law for ITP in the counterclaim, repel the second, third and fourth pleas-in-law for CSO in the principal action, repel the pleas-in-law for CSO in the counterclaim, and grant decree of declarator and interdict as first and second concluded for by ITP. I shall put the case out By Order for further procedure in relation to the amount of profits sought by ITP.
 As has been seen, I have determined both the validity and the infringement issues under reference principally to claim 1 of the patent. Had I held claim 1 to be invalid, there might have been scope for nevertheless finding some of the subordinate claims to be valid, and to have been infringed by CSO. This possibility was only touched on in counsel’s submissions, and if necessary, I would have put the case out By Order for further submissions.
 Before I part company with this Opinion, I wish to record my gratitude to senior counsel on both sides of the bar who conducted the proof, to the Dean of Faculty and to Miss Higgins who addressed me at the hearing on evidence, and to their respective instructing solicitors who prepared orderly sets of working papers, for their assistance in a far from simple case.