[2014] CSOH 57



in the cause





First Defenders:



Second Defenders;


Pursuer: Duncan QC, MacFarlane, solicitor advocate; Simpson & Marwick

First Defender: Di Rollo QC, O'Brien; HBM Sayers

Second Defender: Shand QC; DAC Beachcroft

21 March 2014


[1] In August 2009 the pursuers took up occupancy of first floor office premises in a three storey modern office block at 7 Lochside View, Edinburgh Park, Edinburgh. Thereafter they fitted out the premises with a view to commencing use of them as a call centre in January 2010. The pursuers contracted with the first defenders for the supply and fitting of a coffee dispensing machine. On 17 November 2009 the machine was installed in a staff break-out area, "the Gallery". The position which had been selected for it was on a kitchen-type worktop. It was not attached to the worktop. It rested on top of it. It was connected to the cold water supply using a flexible hose. The hose was attached at one end to the coffee machine. It then passed through a hole which had been made in the worktop to the cupboard space underneath, where it was connected to the cold water supply (a 15 mm copper pipe). On that end of the hose there was a brass spigot. A non-return compression fitting was fitted on the end of the copper pipe. The spigot was inserted in the other end of the non-return fitting. It was connected to it using a brass olive and a nut which was screwed over the olive. The machine was in use to dispense drinks on that day and on subsequent days. There were no reports of any leaks of water. On the morning of 30 November 2009 substantial flooding was discovered in the premises. The olive and the nut were still in situ on the non-return fitting, but the spigot had become completely disconnected from it.

[2] The pursuers seek reparation from the defenders for loss and damage which they suffered as a result of the flooding. Their primary case is against the first defenders. They aver that the first defenders' employees failed to properly secure the connection between the hose and the non-compression fitting. The first defenders aver that the relevant connection was in fact made by an employee of the second defenders, Stephen Noon. On that hypothesis the pursuers aver that Mr Noon failed to secure the connection properly. The defenders deny that the connection was not secured properly. They aver that it was checked after the connection was made and was water-fast. The first defenders aver that it was not reported to be sweating or leaking at any time between 17 November and the discovery of the flooding. The pursuers aver that if there was no sweating or leaking on 17 November "the water pressure was not sufficient at that time to result in water escaping from the connection". The first defenders aver that the connection came apart "because it was interfered with inadvertently or deliberately". In response the pursuers aver:

"None of the people on site required to deliberately interfere with the connection. A load of approximately 30 kilograms was required to physically disconnect the fitting."

[3] The pursuers aver:

"It was the first defenders' duty (ex contractu and ex delicto) to take reasonable care to exercise the degree of skill and competence to be expected of ordinarily competent contractors engaged to install a coffee machine. When installing the coffee machine ... it was their duty to take reasonable care to see that the hose of the machine and the water supply pipe were safely connected...It was their duty to ensure that the connection was secure..."

On the hypothesis that Mr Noon fitted the connection those duties had been incumbent upon him ex delicto and the second defenders were vicariously liable for his breach of them.

[4] The matter came before me for a proof before answer on the issue of liability. The proof occupied five days. The spigot, olive, nut and non-return valve had not been lodged. All but the non-return valve were no longer in the pursuers' possession. At the outset of the proof Mr Di Rollo indicated that he was objecting to the pursuers seeking to lead evidence as to the condition which the missing parts were observed to be in after the flood. While the pursuers were not seeking to prove that any of the components were defective it might transpire that the first defenders had been prejudiced by their inability to have the actual parts examined by appropriate experts. Mr Di Rollo was content that evidence in relation to the parts be led subject to competency and relevancy. Mr Duncan was agreeable to that course being followed. Miss Shand sought to reserve an opportunity to ally herself with Mr Di Rollo's objection in the event of the second defenders being prejudiced by secondary evidence led relating to the parts. The first defenders lodged two sets of the same sort of kits which had been used (comprising, inter alia, hose with spigot, non-return valve, olive and nut).

The evidence on the contentious matters
The pursuer's case
Mrs Sharon Gardiner

[5] Mrs Gardiner was now a manager with the pursuers. In November 2009 she had been a procurement executive. The date of entry of the lease of the first floor at 7 Lochside View had been 3 August 2009. The premises were to be used as the pursuers' main office. They were to house corporate staff and a call centre. She had been involved with the fit out but a consultant, Stephen Aird, had been brought in to supervise most of it. The main contractors had been Sharkey. The project managers had been Thomas & Addison, and the mechanical and electrical contractors had been the second defenders. FESFM Ltd had been engaged to take over the ad hoc maintenance after employees had moved in. There had been a substantial IT fit out. The first defenders had supplied and installed a hot drinks machine in the Gallery. The Gallery contained a small kitchen area. A cold water supply pipe had been installed there by the second defenders.

[6] On the morning of 17 November 2009 the first defenders' employees Richard McFarlane, Joe Feeney senior and Joe Feeney junior had arrived to install the coffee machine and a snack machine. The coffee machine was to be installed on the kitchen worktop in the Gallery. Mr McFarlane and Mr Feeney senior were installing it, but they had not been able to locate the cold water pipe in the cupboard under the worktop. Mrs Gardiner had looked for it too and had not seen it. She contacted Mr Noon. He had arrived within about 15 minutes. He did not have any tools with him, but he had brought a washing machine connection in case one was needed. The water pipe had indeed been in the cupboard beneath the worktop. It was high up and had been partially hidden by a lip of the cupboard. Mr Noon had showed them where it was. He had made a joke about them needing glasses. Mr McFarlane had said he had a connection and didn't need the washing machine connection. Mr Noon had joked, sarcastically, "Do you want me to fit it for you?" "They" had said that wouldn't be necessary, they could do it. There had been some "small talk" before she had left to go back to her desk. Before she had left she had seen someone assuming a position to make the connection - she believed it had been Mr Feeney senior. Tools were laid out and he was on his hands and knees to go into the cupboard. She thought Mr Noon had left with her. She thought there might have been an issue with air conditioning for his attention. The pipe which Mr Noon had showed them had looked like the pipe seen in photograph 6/19 of process. It had had a yellow plastic cap on the end of it like the one in the photograph.

[7] After the machine was up and running cups of coffee and hot chocolate had been dispensed. It had been significantly later in the day before the first defenders' employees had left. Between then and 30 November 2009 she believed that Mr McFarlane had been back in the office on a number of occasions. She recalled that he had brought sugar and stirrers prior to the Friends and Family Day. After that she recalled a further occasion when there had been a discussion about using tokens with the machine.

[8] On Saturday 21 November 2009 about one hundred people had attended a Family and Friends Day in the office. The coffee machine had been on "free vend". Coffee cups, lids and coffee were stored in the cupboard underneath the machine (just below where the hose was connected to the non-return valve), but for that day she thought they had been taken out and put on "a surface". They would probably have been put back in the cupboard on the following Monday.

[9] Between 17 and 30 November 2009 she and other staff - particularly IT staff - were in and out of the office. There would only have been about three or four staff there. She may have used the machine. Other staff may have used the machine. She did not think that security staff would have entered the building between those dates. If there had been a leak between those dates she would have been told about it. No leak had been reported.

[10] On the morning of 30 November 2009 Mrs Gardiner had been telephoned at home by an IT manager. He had informed her of the flooding. She had come in to the office. She had a look at the damage. She telephoned the first defenders to ask that Mr McFarlane attend. It was after 4 p.m. when he arrived. She hadn't been aware of his arrival. She phoned his mobile phone and discovered he was in the Gallery. She had gone to see him. He had said that he had remade the connection using the existing nut, olive and spigot. He had said to her that he had not made the original connection - that it had been Mr Noon. Mrs Gardiner had said that he and Mr Feeney had made it, but he had denied that. She described him as being quite nervous. Mrs Gardiner was concerned that there would not be further flooding. He had said he could fit a different type of connection which was more robust. He had gone to his van to get it. He had fitted it. He had taken the original connection "kit" back to his van.

[11] A meeting with Roger Topping, a loss adjuster instructed by the pursuers' insurers, had taken place at the office a few days after the flooding. Mr McFarlane had been at the meeting. Her recollection was that Mr McFarlane had admitted taking the nut and olive away with him but that he had brought them back to the meeting and had given them to Mr Topping. He may have brought the non-return valve as well - she could not recall. The hose had remained on the machine. The coffee machine had been removed from the building in March 2010. A new coffee company had been engaged by the pursuers to maintain the machine. They had taken everything away to reprogramme it. She believed they had removed the hose and that it had been disposed of.

[12] In cross-examination by Mr Di Rollo, and under reference to page 19 of Dr Graham's report (7/1 of process), she was asked whether she had mentioned to him that around 200 cubic litres of water may have flowed out of the disconnected pipe. She replied "It looked that way."

Stephen Aird
[13] In November 2009 Mr Aird was employed by Strategic Occupiers Facilities. He co-ordinated the relocation of the pursuers from their previous office at Fairmilehead to 7 Lochside View. On 16 November 2009 he took the photograph 6/19 which showed the cold water supply pipe in the cupboard under the Gallery worktop. When photographed the pipe had a white plastic cap on the end. There had been no non-return valve in situ.

Mrs Margaret Reid
[14] Mrs Reid worked for Allander Security. On 30 November 2009 she had arrived outside 7 Lochside View at about 8.45 a.m. The building had been opened already - a colleague would have done that at 5.30 a.m. She went in the main entrance on the ground floor. She heard water coming through the ceiling. Once she went to pursuers' office she was able to hear a moisture alarm - it had been quite dull. There was water on the floor. It got deeper as she walked towards the Gallery. It was coming from the cupboard under the coffee machine. She opened the cupboard door. The white flexible hose fell out, as did sugar and tea bags. The hose was detached from the pipe. Water was gushing out of the pipe. She called Kevin MacFarlane the Facilities Manager. He arrived about 9 a.m.

[15] Allander Security's duties on the night shift involved going in to each of the buildings at Edinburgh Park to make sure windows were closed and to do the "lockdown". The buildings would then be opened up for business at about 5.30 a.m. Any leaks spotted by security staff were to be reported.

Kevin MacFarlane
[16] Mr MacFarlane was a building supervisor with the Miller Group. His responsibilities included the day to day running of 7 Lochside View. When he arrived in response to Mrs Reid's call he found the stopcock and switched the water off. His line manager, Jacqueline McAinsh, arrived shortly afterwards. She took the photographs 6/17/1 and 6/17/2 of process. The photographs showed the hose, non-return valve and nut as they had been when he had first seen them that morning. Between 17 and 30 November 2009 he would have been in the building once or twice a day, Mondays to Fridays. There had been no reports to him of leaks.

Jacqueline McAinsh
[17] Mrs McAinsh was a property manager with Miller Developments. She confirmed taking the photographs 6/17/1, 6/17/2 and 6/17/3 at about 9.37 a.m. on 30 November 2009. During the fit out she had probably been in the building every other day talking to contractors. No report had been made to her of any leak prior to 30 November 2009.

Douglas Hopkins
[18] In November 2009 Mr Hopkins had been employed by FESFM Ltd as a service engineer (mechanical side). He dealt mainly with plumbing. Around 9a.m. on 30 November 209 he was asked to attend at the pursuers' office. When he arrived at the Gallery the water had been turned off and the hose and non-return valve were as shown in photograph 6/17/1. He used a couple of spanners to unscrew the nut. It wasn't as tight as he had expected. Underneath it was a brass olive. The olive looked perfectly normal as if it hadn't been used. Normally he would expect the olive to be squashed down and crimped; to be deformed to some extent. When a nut was screwed down on an olive on a copper pipe it would bend and cut down into the copper of the pipe. But where what was being connected was made of brass (like the spigot) the nut had to be very tight because brass didn't give as easily as copper. Once he had removed the olive and nut he had put them on the spigot. They had gone on easily. He had concluded that the olive wasn't deformed and that the nut hadn't been tightened properly.

[19] In cross-examination Mr Hopkins confirmed that his conclusion that the nut had been insufficiently tightened was based upon his belief that with a properly tightened nut the olive would have deformed.

Roger Topping
[20] Mr Topping is a chartered loss adjuster. He was first instructed by the pursuers' insurers on 30 November 2009. He had attended a meeting on 2 December 2009 at the pursuers' office. Mrs Gardiner, Mr McFarlane and the first defenders' managing director had been present. Mr McFarlane had said that when he had come to install the machine a non-return valve had already been fitted to the end of the cold water pipe. He didn't know who had fitted it. He said that Mr Noon had volunteered to fit the hose and had done so. Mr McFarlane had given him the non-return valve which he had removed when he had fitted a new valve. Mr McFarlane had told him that he had remade the connection using the existing nut and olive. Mr Topping gave evidence that the olive might have provided good evidence of how tight the nut had been, but if it had been re-used that evidence might have been corrupted. He had asked Mr McFarlane for "the fitting". He thought he may have asked for the olive and the nut - that he had asked him for all he had. He had expected to get all of the relevant parts. What he had been given had been the non-return valve, nothing else. Mr Topping had not instructed any specialist expert input as to the cause of the failure of the connection.

[21] In re-examination Mr Topping indicated that his understanding "from discussions" was that the olive had simply been thrown away. He could not remember exactly what had been said about the olive at the meeting. He could not recall if he had asked specifically for it: he observed "I didn't take it that far. I asked for the fitting and expected to get what there was."

Mrs Daphne Wasserman
[22] Mrs Wasserman is a is a mechanical and materials engineer. She is a Technical Director with the engineering firm Cadogans. In October 2013 she was instructed by the pursuers to prepare a report. She was asked to comment on the cause of the leak. She was also asked to comment on the question of how a reasonably competent plumber, acting with ordinary skill and care, would have approached making the connection. Her report is 6/7 of process. For the purposes of preparing her report she had been able to consider the report (7/1 of process) of the expert instructed by the first defenders, Dr Graham, and the photographs in that report. She had not had the opportunity to examine any of the actual components which had been used to make the connection: "I gather that they may not be available." In examination-in-chief she indicated that she had been aware of comments made about the olive and its condition after the failure. She was asked "How significant is the evidence of re-use of the olive and the nut?" She replied "It is quite significant." She was then asked "To what extent does your opinion evidence depend on assessment of the actual condition of the olive [after the leak]?" Her response was "It is part of the evidence that leads me to conclude that the nut and olive were not tightened sufficiently." She observed that the fact the olive could be re-used suggested that it could be taken on and off the spigot with relative ease. That was quite significant. She added "There is also other evidence independent of the condition of the olive which I rely upon for my opinion."

[23] Mrs Wasserman dealt with the cause of the leak in section 4.1 of her report:

"4.1.3 Cause of the leak Dr Graham has shown that under some circumstances the hose can be forced out of the fitting by water pressure. He also notes that at the time of his visit the water pressure adjacent to the coffee machine was about 2.4 bar but that on occasion it had risen to 5.7 bar. In my view, the most likely explanation for the failure is that the nut was not tightened sufficiently. Under a relatively low water pressure no leak would be evident. If, at some later stage, the water pressure increased the hose could be forced out of the fitting. Dr Graham also noted that the hose could be pulled out of the fitting if sufficient force was used. During the period of the installation and the failure the building was not occupied. The cupboard was used to store some plastic cups but the kitchen area and the coffee machine did not have heavy use. It is possible that a contractor may have moved the coffee machine between November 17th and November 30th. As the hose passed through the counter top I would not expect a large force to be transmitted to the connection as a result of this. I therefore think it is unlikely that the hose was pulled out of the fitting by a person.

4.1.4 Conclusion on the cause of the leak On the balance of probabilities, therefore, I am of the opinion that the nut on the fitting was not tightened sufficiently and that the hose was forced out of the fitting by an increase in water pressure."

[24] In section 4.2 she considered the actions of a competent plumber:

"4.2 Actions of a competent plumber

.... When fitting the hose the compression nut should be tightened to the correct level. Dr Graham quotes one hose manufacturer as stating that the nut should be tightened to a torque of 4 to 5 Nm. Dr Graham's tests suggest that if the nut was tightened to this torque the joint would withstand a water pressure of 12 bar. I have seen no evidence that either Defender had a torque wrench. If they had used one it is likely that the joint would have been correctly tightened. The alternative method often adopted is to tighten the nut finger tight then continue to tighten it by a certain amount, for example a quarter turn, using a conventional spanner. This method is less accurate as the amount of turn has to be estimated. Tightening using a conventional spanner to turn the nut by a certain amount is a technique regularly used by plumbers. However, it must be done carefully to ensure sufficient tightening without over-tightening the coupling ...."

[25] In section 4.3 she considered the appropriate method of testing for water tightness. She concluded that it would not be normal practice to carry out a pressure test on an individual fitting: rather, common practice would be to check the fitting visually for leaks.

[26] In examination-in-chief Mrs Wasserman conceded that the activity in the office and the use of coffee machine appeared to be greater than she had understood when she had prepared her report: but that was "of small importance to my reasoning". She accepted Dr Graham's test results, but she did not agree with his conclusions. She now believed that the reference to 4 to 5 Nm in the manufacturers' guidance (and the associated diagram of a wrench) (Appendix A to Dr Graham's report) referred to the torque to be applied to the connection between the hose and the coffee machine, not the connection to the non-return valve. She departed to that extent from what she had said in her report. She thought it unlikely that the leak would have been caused by external force being applied to the connection. The sort of force Dr Graham contemplated, 30 kg, was considerable. From the photographs it looked like the hose had not been taut - there had been some slack - making it less likely that such force could have been applied inadvertently. If someone had inadvertently pulled the hose right out it would have leaked immediately and the person who did it would have been likely to do something about it. From photograph 6/17/2 one more screw thread was visible between the nut on the hose side of the non-return valve and the centre of the valve than appeared between the nut on the opposite side and the centre of the valve. From examining the specimen fittings lodged in court she thought one thread equalled a complete turn of the nut. She clarified the only information about water pressure which she had had were (a) that after the leak the pursuers had commissioned a period of continuous monitoring of the water pressure at the local main between 5 and 12 December 2009; the pressure logged had been about 5 bar with minor variations above and below that figure; (b) when Dr Graham visited on 7 October 2010 he noted that the water pressure a short distance upstream of the coffee machine was 2.4 bar, and from a sweeping telltale had been a maximum of 5.7 bar at some time. She accepted that the connection appeared to have been sufficiently tightened to be leak‑free until about 30 November. Her explanation was "It may be explained if the pressure was relatively low for the first 12 days but then rose and caused the fitting to come apart."

[27] In relation to what a competent fitter would have done she had looked at other manufacturers' recommendations and information published by the UK Copper Board. These suggested tightening to finger tight and then a further three- quarters of a turn up to one and a quarter turns.

[28] In cross-examination Mrs Wasserman indicated that she had been told that the original components - other than the non-return valve - had not been retained. She had not enquired further about them. She had been shown the non-return valve. It was the same as the specimens. She accepted that the nut, olive and spigot could have been of evidential value: more so the olive and the spigot than the nut. (Unless there was a fault in the nut - which had not been suggested). The olive and the spigot could have been tested, in the same way as Dr Graham had tested specimens. It would have been useful to see if the olive could be easily moved on the spigot. She said her understanding of the recommended approach to tightening was to tighten to about half a turn to three-quarters of a turn past finger tight, and if the joint still leaked to tighten a little bit more. In addition to looking at manufactures' guidance and the UK Copper Board material she had looked at DIY website discussions. She had done this research after the preparation of her report. She had not contacted the suppliers of the hose. She had not been asked to consider the possibility of deliberate vandalism.

[29] In re-examination Mrs Wasserman confirmed that in her view where the connection used a brass spigot and a brass olive the nut should be tightened to between half a turn and three quarters of a turn past finger tight and if leaking tightened by a small further amount. She considered she was able to provide her opinions on the basis of a desk top study. It would have helped to have had the parts but she was nonetheless able to provide an opinion without them. If the olive and spigot had been re-used twice after the leak they would have been of very little evidential value. The olive could well be very deformed. The spigot would only be useful if there more than one set of marks on it - it might show it had been differently inserted on different occasions. While she did not have the figures to hand she strongly suspected that brass would require a higher force to deform plastically than copper would.

Stephen Noon
[30] In November 2009 Mr Noon was a project manager in the second defenders' mechanical division. He was qualified as an electrician and as a gas fitter and engineer. The second defenders installed the pipework in the petitioners' office. After the contract works had been done the second defenders were asked to provide, as an extra, a water point to a vending machine in the Gallery. On Mr Noon's instructions one of the second defenders' plumbing engineers did the work. On 17 November 2009 Mrs Gardiner telephoned to say that the supply point could not be located. He had driven to plumbing suppliers and picked up a couple of fittings that might be required - a 90 degree compression elbow and a "washing machine valve". On arrival at the Gallery he had located the pipe. He showed it to Mrs Gardiner and the two men who were installing the machine. The end of the pipe had been capped off with a push fit fitting as shown in photograph 6/19. There had been a little bit of banter. Mr Noon had asked if either of the fittings he had brought was required. The men had said no. They had got on with what they were doing. Mr Noon had remained in the vicinity of the Gallery. He did not recall if Mrs Gardiner had asked him about air conditioning at that time. When they had finished Mr Noon had turned the water back on. He had checked visually that there had been no leaks. He considered that he had had a responsibility to do that.

[31] During cross-examination by Mr Di Rollo Mr Noon confirmed it had been a little difficult to see the pipe because of the lip of the cupboard. He had been confident that his men had installed the water pipe "but it was possible the final connection wasn't correct" so he had stopped at plumbing suppliers to pick up a couple of items that might be needed. If he had had to install the items he had bought he would, reluctantly, have put them together by hand and tightened them with spanners from his car. He believed he may have taken his screwdriver and a set of Gordon grips - pliers for water pipework. He had those tools in his hand, the other items would have been in his jacket pocket. He didn't bring a toolbox or a bag. He had never connected a coffee machine before. He had connected lots of washing machines. He removed the push head which was capping off the pipe then he left the men to get on with it. He had not put anything on the pipe. If he had had to, he would have. He had jokingly said when he had pointed it out "Do you want me to connect it up as well?" He had not meant it - it had been "a slight dig at them". When the men told him they were ready he had turned the water back on using his screwdriver. He had then checked the downstream pipework from the stop valve to the connection which had been made to ensure that there was no leakage. He had been clear there wasn't. He visually looked at the various joints and he would have run his hand along to ensure that there was no water. He said he had a responsibility to do that.

[32] Under cross-examination by Miss Shand Mr Noon indicated that he was present when the connection was made but he wasn't paying attention. He had been in the general, but not the immediate, vicinity. He may have been talking to Miss Gardiner. He had connected washing machines at home. He had connected dishwashers professionally before he worked with the second defenders. The non-return valve which had been used in the connection was completely different from a washing machine valve.

The first defenders' case
Richard McFarlane
[33] In November 2009 Mr McFarlane was a senior engineer with the first defenders. He had been employed with them since 2000. He had been in the vending machine industry since 1970. He was a time-served electrician. On 17 November 2009 he and two colleagues, Joe Feeney senior and Joe Feeney junior, had arrived to deliver and install three vending machines. A (table-top type) coffee machine was to be installed on a worktop in the Gallery. Mrs Gardiner showed them where. He and Joe Feeney senior unpacked the machine and lifted it on to the worktop next to a hole in the worktop which had already been cut for the flexible hose to go through.

[34] The installation kit which came with the machine included a flexible hose with a brass spigot on the water connection end, a non-return valve, and nuts and olives. With such kit the non-return valve went on the end of the water pipe and the spigot was inserted inside it. It was then secured in place by slipping an olive over it and screwing the nut over the olive, tightening it to make a seal. This was a standard task of a sort which he had done countless times over a period of forty years. With such a connection he would use an adjustable spanner to get it tight using about three-quarters of a turn of the nut. That was what the manufacturers recommended and that was what he normally did.

[35] After the machine was in position on the worktop Mr McFarlane and his colleagues were unable to locate the water pipe. They contacted Mrs Gardiner. She could not see it either. Mr Noon had been asked to come. Mrs Gardiner had said he was the lad who organised the pipework. When he arrived Mr Noon got on his knees and located the water pipe. It had been very close to the underside of the worktop. Mr McFarlane thought that the pipe had a non-return valve fitted to the end but he could be mistaken. It had been quite embarrassing. There had been a bit of banter. Mr Noon had then said "Do you want me to connect it?" Mr McFarlane had said "Well you are there, carry on." Mr Noon had seemed to know what he was doing; he hadn't asked any questions. Mr McFarlane had assumed he was a plumber. The hose had already been dropped through the hole. Mr McFarlane thought that Mr Noon had had a small toolbag with him. It was some sort of bag. Mr Noon had said "That's it." Then Mr Noon had gone along to the cupboard with the water supply and had turned it on. He had said "That's you ready to go." At the end of the job, at about 3 p.m., Mr McFarlane put his hands round all the joints to see if there was any sweating or leaking. He ran his hand round the non-return valve where it connected with the hose. There was no dampness. At that point the machine had been running for about four hours.

[36] Between 17 November and 30 November Mr McFarlane had been back at least three times. The first visit had been to adjust the drink levels - for it to dispense quantities for staff mugs. He would have had no reason to go into the cupboard on that occasion. On the second occasion he upgraded the machine so that it accepted tokens. He had not gone into the cupboard on that occasion. The third occasion was the Family and Friends Day. His daughter was an employee of the pursuers. The coffee machine was in operation and had been on free vend. He had had to restock it because it had been used so much. He had used the coffee and milk in the cupboard. The stock was directly below the connection. Had it been leaking the stock would have been wet. It wasn't.

[37] On 30 November 2009 he was asked to attend at the pursuers' office in connection with a leak. He knew it could only be the coffee machine. (Neither of the other two vending machines were connected to the water supply.) It was later in the day before he got there. He went to the Gallery. The cupboard door was open and the hose was hanging out. The nut and olive were on the hose. The scenario shown in photograph 6/5/7 of process was the one which greeted him. It looked like the connection had been disconnected. He reconnected the hose and parts because he wanted to find out where the problem lay. He switched the water on and turned the machine on. The machine and the connection were working as they should. He made himself a cup of coffee. Mrs Gardiner had arrived. She asked him if he knew what had happened. He said no, but that he had reconnected the machine and it was working. She had not been comfortable with that and had asked if anything else could be done. Mr McFarlane had said he had a safety block in the van. She asked him to fit it. He had fetched it, undone the connection, removed the return valve and remade the connection using the block and the same nut and olive. He had explained to Mrs Gardiner that he had not found any fault but that the water block would shut off the water if there was an incident. He had put the non-return valve in his van.

[38] Later he and the first defenders' managing director had attended a meeting with Mr Topping and Mrs Gardiner. He had told Mr Topping about remaking the connection using the water block. Mr Topping had asked what had happened to the equipment used. Mr MacFarlane had told him he had the non-return valve. He had given it to him.

[39] During cross-examination Mr McFarlane accepted that it had been a little unusual for them to leave it to someone else to make the connection and that was not his habit. However, some customers did not allow the first defenders to do it, preferring to make their own arrangements. In addition, sometimes when they came to make a connection plumbers had already fitted a non-return valve. He adhered to his view that Mr Noon arrived about five minutes after being called - he didn't think it was possible it was as long as fifteen to twenty minutes. He felt sure that there was a non-return valve on the pipe already. When it was put to him that he or Mr Feeney senior, not Mr Noon, had connected the hose to the non-return valve he replied "No. It is a definite. I did not connect it. Mr Noon did. I have a clear recollection of who did this work." He and Mr Feeney had been standing up to the left side of Mr Noon while he did the work. He remembered this occasion well because Mr Noon had showed them the pipe and it had been highly embarrassing. When he had returned on 30 November and reconnected it he had been trying to find out where the leak had come from and whether a component had failed. He didn't recall Mrs Gardiner, on 30 November, raising the issue of who made the connection. Her concerns appeared to be more what had happened and how she could prevent it happening again. He did not recall mentioning to Mr Topping that he had re-used the nut and olive.

Patrick Joseph Feeney senior
[40] In November 2009 Mr Feeney had been employed by the first defenders as a service engineer. He was not a time-served tradesman but he had worked in the vending machine industry since he was 16. (He was 49 at the proof). When they had arrived at the pursuers' office on 17 November Mrs Gardiner had told them where the machines were to go. She said that there was a copper pipe sticking up on the Gallery worktop where the coffee machine was to go. When he saw it Mr Feeney had asked her whether it was live because it did not have a cap on it. She went to get someone who knew. He had not looked in the cupboard at that time and he did not think anyone else had. Ten or fifteen minutes later she had returned with a gentleman. He had assumed it was the person who had dealt with the water supply. Mr Noon had lifted the pipe out of the hole - it had merely been a loose piece of pipe marking where the hole was. Then he had got down on his knees and had pointed out the water pipe in the cupboard. The pipe had had a non-return valve on the end of it. Mr Noon had said something about them needing glasses. Mr Noon had then said as he was down there anyway he would just connect it. The hose had been passed down to him and he had connected it. He had had tools with him in a handy-tools belt. Mr Feeney thought that he passed Mr Noon the nut and olive to make the connection. Once he had made the connection Mr Noon went to the stopcock and turned the water on. Mr Noon had then checked the joints. Mr Feeney said that he would have checked the joints too. He always checked both ends of the hosepipe. He was shown photograph 6/19 (which showed a pipe with a cap on the end rather than a non-return valve). He said that if that was a picture of the pipe at the time then he obviously didn't see a non-return valve on it when he looked in the cupboard. He suggested that he must have assumed from looking at the photographs of the pipe after the event that the non-return valve had already been fitted. Quite often a non-return valve would have been fitted already when he came to make a connection. Mr Noon could have fitted it when he made the connection.

[41] Under cross-examination by Miss Shand Mr Feeney clarified that he had been shown some photographs by a lawyer about three weeks before the proof. He had felt stupid when Mr Noon had removed the loose piece of pipe, pointed out the water pipe, and joked with them that they needed glasses. The loose piece of pipe seen lying at the base of the cupboard in photograph 6/19 could have been the piece used to mark the hole. It was put to him that Mr MacFarlane had said they had looked in the cupboard but could not see the pipe. Mr Feeney replied that may well have been the case. He did not remember Mrs Gardiner looking in the cupboard. The reason she had gone to get Mr Noon was to see if the pipe sticking up was live, not because they couldn't find the water pipe in the cupboard. Mr Feeney had bent down to look in the cupboard and had seen the pipe when Mr Noon had been down there. Mr Feeney had put the flexi-pipe through the hole and Mr Noon had fitted it. Mr Noon had had a tool tidy belt - like "a wee bag"- strapped to his leg. He assumed Mr Noon must have fitted the non-return valve. He was adamant that he did not make the connection. He checked the fittings by hand after they had been fitted - to make sure there were no sweats or drips from the joints. He had worked for very many years doing this sort of work and he had never had a leak. He couldn't say categorically that Mr McFarlane had checked them on this occasion but that was what he normally did. Usually they both checked, one after the other. He was asked why Mrs Gardiner would say that Mr Mcfarlane had declined Mr Noon's offer and she had seen Mr Feeney at the cupboard preparing to do the job if those things were not true. He replied:

"No - I can't explain it. I know for a fact 100% what I am saying is true. When I tell you I didn't fix it - if I had done it I would have said. If I had done it I would have told you."

[42] Under cross-examination by Mr Duncan Mr Feeney accepted that he should have looked under the worktop at the outset. He could not remember doing that. It was suggested to him that for he and Mr MacFarlane to let someone else make the connection suggested a degree of casualness on their part. He agreed. It was put to him that in fact it was Mr McFarlane or him who did it. He replied "100% not". He was asked how he would have approached it if he had made the connection. He said he would have put the olive and nut on and tightened the nut up to hand-tight. He would then have turned the nut a further half turn, or slightly more, to make sure it was watertight. In 27 years he had never had a leak.

Dr Jan Graham
[43] Dr Graham is a consulting engineer. He is a partner in Geoffrey Hunt & Partners. On 19 May 2010 he was instructed on behalf of the first defenders to attend at the pursuers' office to inspect the equipment present and to examine components which had been retained by Mr Topping. He did so on 7 October 2010. Subsequently he carried out further investigations and prepared a report dated 21 December 2011 (7/1 of process). Part of his investigations involved carrying out tests on fittings of the same type as those which had been employed to make the connection. Dr Graham was present in court during the evidence of the factual witnesses.

[44] At the time of Dr Graham's attendance on 7 October 2010 the original flexible hose had been replaced (in about January/ February 2010) and other changes had been made to the fittings connecting the coffee machine to the water supply. Dr Graham noted in paragraph 3.2 of his report:

"As a result, the only component of the original pipework that remained at the time of my attendance was the body of a double check valve that Mr Topping had retained... This was the least evidentially significant component of the original installation: the brass male spigot on the end of the original flexible hose, and the copper or brass olive installed within the compression fitting, the condition of either or both of which may have provided physical evidence to confirm the mechanism of failure of the joint, have apparently been disposed of."

[45] Dr Graham explained that the pursuers had commissioned a five day period (5 - 11 December 2009) of continuous monitoring of water pressure at the local main. Mains pressure averaged 4.96 bar (48.6m) with only slight variations (a peak of 50.05m and a minimum of 42.14m). He had seen no evidence as to what mains water pressure was at any earlier time. The local supply branch serving the coffee machine had a pressure gauge installed. At the time of his visit on 7 October 2010 Dr Graham noted that the water pressure a short distance upstream of the coffee machine was 2.4 bar. A sweeping telltale indicated that at some point pressure had reached a maximum of 5.7 bar. Mrs Gardiner had informed him that it was estimated up to 200 cubic metres of water had escaped during the leak. If that was indeed so the discharge was likely to have taken place over a period of at least 10 hours (but it could have been as long as 30 hours). It depended on the water pressure at the time and the applicable discharge co-efficient.

[46] Dr Graham explained that the brass spigot was much harder than a copper pipe and, because it was a machined fitting, it was also much rounder and smoother. By comparison a copper pipe was out of round, unsmooth and comparatively soft. It was much more liable to be indented by an olive in the course of compression. That didn't happen with brass. A compression join on to brass tended to be more secure against leakage than one on to copper because a closer join was achieved; but a join on to copper tended to be more secure against movement. Ordinarily, a compression join on to a copper pipe could be expected to withstand 70-90 bar before the join separated. This was a fortuitous incidental mechanical benefit, because a compression joint was not intended to be a mechanical joint. Its purpose was simply to make the joint leak-tight. Pipework should be independently supported to resist thrust pressure. The conventional requirement for leak-tightness of joints was that they should be leak-tight up to 12 bar.

[47] Dr Graham spoke to the tests which he carried out on 22 August 2011 using the hose kits supplied to him by the pursuers. These were recorded in section 6 of his report. He noted that the flexi-hose was marked for a maximum pressure of 12 bar. In Test Series 2 he made a connection using a brass olive and tightened it to a one-quarter turn of the nut past finger tight (a torque of 6.6 Nm). He then increased water pressure in 1 bar increments. A slight weep commenced at 5 bar. At 8 bar the connection held with no motion and no pressure drop for 5 minutes. He increased the water pressure in 1 bar increments to 12 bar. The leakage rate did not appear to increase. He pulled firmly on the end of the hose and found that the brass spigot could fairly readily be extracted from the fitting leaving the olive behind. He described the force used as being akin to a hearty handshake or pulling a garden hose off its hoserail; it had not been a bracing tug-of-war type pull. He dismantled the connection and found that the olive could be re-installed on the spigot. He remade the connection to one-quarter turn past finger tight (6.6 Nm). He applied 15 bar pressure. The connection wept but did not appear to be at risk of separation. He increased it to 18 bar with the same result. It was then increased to 20 bar at which point the leakage rate increased and the spigot eased slowly out of the connection over about 5 seconds. Dr Graham repeated the test with greater tightnesses of the nut. Where the nut was tightened to 7.7 Nm (about one twenty-fourth of a turn tighter than before) a very slow leak occurred at about 5 bar and the connection eased apart at 24 bar. Tightened to 8.2 Nm it eased apart at 28 bar. Tightened to 8.5 Nm it dripped slowly at 15 bar and started to move at 28 bar: upon dismantling the olive could still be removed and replaced on the spigot with light finger pressure. Tightened to 8.8 Nm (just short of one-third of a turn from finger tight) slow leakage commenced at about 20 bar. The leakage rate increased significantly at 30 bar and the connection mobilised at 31 bar. Upon dismantling the olive was no longer free but could be removed from the spigot using the compression nut as a "drift", and the olive could be re-seated after careful alignment. Tightened to 9.5 Nm (about nine twenty-fourths of a turn past finger tight) a slight weep commenced at 15 bar, and a slow drip at 20 bar. Pressure was raised incrementally to 30 bar and then 3 bar with no apparent difficulty. The spigot pushed through the olive at 40 bar. Upon dismantling Dr Graham found the olive to be a very close fit but it was still just possible to reinstall it on the spigot. There was no sign of any gross scoring on the spigot but the spigot's surface appeared slightly burnished. There were no plastic compression rings visible inside the spigot. Dr Graham reassembled the connection, tightened to 10.4 Nm (five-twelfths of a turn past finger tightness), and applied and maintained 45 bar pressure. The spigot moved and popped out of the fitting in about 5 seconds. There remained no obvious sign of damage to the spigot.

[48] Dr Graham concluded that the connection made on 19 November must have been tightened to at least a one-quarter turn past finger tight - otherwise it would have leaked freely from the outset. If it had been tightened to one-quarter turn past finger tight it would have oozed or wept at about 5 bar. However, even in those circumstances the instantaneous failure pressure would have been in excess of about 13 bar - far in excess of the maximum water pressure to which, on the evidence, it may have been exposed. If it had been tightened to one-third of a turn past finger tight (still a relatively light tightening torque) the failure pressure of the connection would have been in excess of 30 bar. Tightened to five-twelfths of a turn, 45 bar pressure was required to cause failure; but even then the olive could be reinstalled and the spigot was undamaged. It followed that the fact that after the incident the olive could be reinstalled on the spigot was not an indication that the nut had been insufficiently tightened. Mr Hopkins' observations in that regard had not been well founded. While with a compression joint on a copper pipe and a copper olive some deformation might have been expected with a sufficiently tightened nut, that was not so with a brass olive on to a brass spigot.

[49] The manufacturer's instruction for use of the fitting were appended to Dr Graham's report. These appeared to indicate "Brass fittings maximum torque 4 to 5Nm". Under the heading "Post Installation" was the instruction "Verify all connections are secure and leak free." Dr Graham was satisfied from his test results that an installation torque of 4 to 5Nm would have been sufficient to provide an instantaneous failure pressure of the connection greater than 12 bar.

[50] If the connection made had been capable of being separated by a water pressure of 5.7 bar it would have leaked freely in the period between 17 and 30 November. There was no evidence of any such problems. To be leak-tight at a pressure of 2.4 bar the nut would have to have been tightened at least one and one-quarter flats (one flat of the nut was one-sixth of a turn) past finger tight. At that tightness the failure point would have been in excess of 11 bar.

[51] For these reasons Miss Wasserman's theory of how the failure occurred appeared to him to be extremely unlikely. In his career he had seen a number of failures of compression fittings In none of them had the joint been leak-tight when fitted, leak-free for a substantial period, but then failed with no intervening cause. What was being suggested was a very unusual scenario. A more likely cause was that the failure had been the result of interference with the connection - inadvertent or deliberate. If, say, the connection had been tightened so as to have a failure pressure of 20 bar it would have had a reserve strength of 15 bar (allowing for a water pressure of 5 bar). In such circumstances a pull force applied to the hose of 30kg would be sufficient to mobilise the connection. That force could have been induced by no more than a sharp yank, such as could have occurred if someone was attempting to remove something from the cupboard when it was entangled with the hose; or by moving the machine during cleaning or the like.

[52] Dr Graham indicated that it would have been of value to him to have had the original components - particularly the spigot and the olive. They might have had marks on them which assisted in determining how tightly the nut had been secured. It was less likely there would have been marks inside the nut but sometimes there were, and sometimes they did provide an indication of the turns applied to them. Even if a connection had been remade twice after the failure using the nut, olive and spigot examination of them could still be of value. He would have liked to have put the parts under a microscope. Sometimes it was possible to discern overlapping markings, and to say the order in which markings had been made.

[53] Under reference to photograph 6/17/2 and paragraph 4.15.2 of his report Dr Graham observed that the nut on the hosepipe side of the non-return valve appeared to have been tightened tighter than the nut on the copper pipe side of the non-return valve. He did not consider that that assisted in determining the cause of the failure. If he had had the original components it might have been possible to reproduce the position seen in the photographs. The test results he had were the best available evidence.

[54] In cross-examination by Mr Duncan Dr Graham agreed that the precise magnitude of the external force required to produce failure depended upon how tightly the connection was made. The example of 30kg which he had given applied where there had been a one-quarter turn past finger tight (6.6 Nm) and water pressure of 5 bar. He agreed that in the case of the coffee machine being moved force would only be applied to the joint if the hose was pulled taut. A small movement of the machine would not have done that - it would have to have been moved a foot or two before the hose became taut. It would not have been difficult to slide the machine along the worktop. He was in no doubt that that sort of force could have been generated by movement of the coffee machine. That was one possibility. The level of force involved (30 kg) was about the same as would be generated by a sharp application of a car handbrake. It was put to Dr Graham that there was an inconsistency between paragraphs 6.11 and 7.13 of his report in respect that in the former case a firm pull had produced failure whereas in the latter a sharp yank had been required. Dr Graham denied that there was any inconsistency. Greater external force was being applied in the second instance. His opinion was that a joint which was leak-free at 2.4 bar, and whose failure pressure was 11 bar, would not begin to mobilise at 5.7 bar. The mobilisation point would be lower than the instantaneous failure point. It would be likely to begin mobilisation at a point about 80% of 11 bar (the instantaneous failure point), that is at about 8.8 bar. A joint could reach the point where it mobilised but take further time before it reached the point where it failed. He agreed that conventional guidance in relation to compression fittings tended to be for tightening to about three-quarters of a turn past finger tight: but that was not directed towards the particular circumstances here of a connection between a brass olive and a brass spigot. If the nut had been tightened to that extent here the failure pressure would have been grossly in excess of 45 bar and the olive would have been locked on the spigot.

Second defenders
[55] The second defenders led no evidence.

The pursuers' submissions
[56] Mr Duncan moved the court to sustain the pursuers' first plea-in-law and allow a proof on quantum between the pursuers and the first defenders. In the event of the court holding that Mr Noon had made the connection he moved that the pursuers' first and second pleas-in-law be sustained and that a proof on quantum be allowed.

[57] The evidence of Mr Noon and Mrs Gardiner should be accepted as to who made the connection. The evidence of Mr Feeney and Mr McFarlane should be rejected.

[58] Mrs Wasserman's evidence as to the likely cause of the failure of the connection should be accepted. While the onus was on the pursuers to establish the cause of the failure on the balance of probabilities (Rhesa Shipping SA v Edmunds [1985] 1 WLR 948) it was legitimate to proceed by way of exclusion if that process was approached properly (McGlinchey v General Motors [2012] CSIH 91; Clerk and Lindsell, Torts (20th ed.), para. 2-08; Drake v Harbour [2008] EWCA Civ 25, per Toulson LJ at para. 28). On the evidence the application of external force could be excluded. That left Mrs Wasserman's theory. Mrs Wasserman was a more impressive witness than Dr Graham. Support for her explanation was to be found in the evidence of Mr Hopkins and in the photograph 6/17/2. Dr Graham had been somewhat combative in the witness box. He had not been prepared to concede matters which he ought to have. He had sought to bamboozle the court with calculations. His evidence contained inconsistencies - particularly between paragraphs 6.11 and 7.13 of his report. There was no evidence of any external force having been applied, and Dr Graham's examples of circumstances in which it might have been were implausible. Had external force been applied it would have been likely to have led to immediate failure. The person responsible would have done something about it. Deliberate interference was very unlikely.

[59] In the event that the failure was caused as the pursuers aver then the first defenders' would have been in breach of their duty (ex contractu and ex delicto) to exercise the degree of skill and competence to be expected of ordinarily competent contractors engaged to install a coffee machine. In this connection Mr Duncan relied upon the evidence of Mrs Wasserman and Mr McFarlane that such contractors would have tightened to three-quarters of a turn past finger tight. He relied upon the evidence of Mrs Wasserman, Mr Hopkins and the photograph 6/17/2 as establishing breach of the duty.

[60] The objection to the admissibility of evidence of the condition of the olive, spigot and nut should be repelled. The general principles applicable were not in dispute: Scottish & Universal Newspapers Ltd v Gherson's Trustees 1987 S.C. 27; Peacock Group plc v Railston Ltd 2007 SLT 269; Haddow v Glasgow City Council 2005 SLT 1219. Mr Duncan stressed that the pursuers do not rely on evidence from Mr Hopkins that the olive was not deformed and was able to be re-used. What they relied on was his evidence that when he untightened the nut it was not as tight as he had expected it to be. It was not possible to say what had happened to the olive and the nut after the leak. Mr McFarlane's evidence that he had re-used them ought not to be accepted. He had not given them to Mr Topping - Mrs Gardiner's evidence to that effect was plainly wrong. The evidence was that the hose was later disposed of, but there had been no suggestion at that time that it had been important to retain it. No blame should attach to the pursuers for the non-availability of any of the items. There was no prejudice to either defender. Mrs Wasserman said that examination of the olive and the spigot would have been likely to be of little assistance if they had been re-used twice since the failure. Her evidence should be preferred to Dr Graham's on that matter.

[61] If, contrary to the pursuers' submission, the court was satisfied that the connection had been made by Mr Noon rather than by one or other of the first defender' employees, its failure would have been caused through Mr Noon's negligence. The second defenders would be vicariously liable for Mr Noon's breach. In that event the failure would also have been caused through the first defenders' breach of contract - they would have failed to exercise ordinary care that the connection was made securely.

The first defenders' submissions
[62] Mr Di Rollo insisted on his objection to the admissibility of evidence concerning the condition of the nut, olive and spigot. In this connection he agreed that the relevant principles were to be found in the authorities which Mr Duncan referred to. On being pressed as to which particular passages of evidence ought not to be admitted he confined his objection to Mr Hopkins' evidence of what he found when he unscrewed the nut and examined and moved the olive, and to Mrs Wasserman's observations in relation to that evidence. The olive, nut and spigot had been in the pursuers' possession after the failure - the inescapable fact was that they had not taken proper steps to preserve them, and that therefore there had been fault on their part. The defenders were prejudiced because expert examination of the parts might have provided evidence relating to the cause of the failure. Dr Graham's evidence in that connection should be accepted. Even Mrs Wasserman had conceded that examination of them could have been useful, though she doubted whether that would be so if they had been re-used twice. Mr Topping acknowledged that it would have been useful to have them. If the objection was not sustained and the evidence was admitted the Court should bear in mind the prejudice caused to the defenders because of the absence of the parts when determining whether the cause of the failure which the pursuer suggested had been established (Stirling Aquatic Technology Ltd v Farmocean AB (No. 2) 1996 SLT 456).

[63] In any event decree of absolvitor should be pronounced. While it was accepted that, whoever made the connection, the first defenders had a duty to exercise the ordinary care of installers that it was securely made, the pursuers had failed to prove (i) that it had not been securely made; (ii) what the standard of care of an installer was; (iii) that that standard had not been attained; and (iv) that any such breach had caused the failure.

[64] The pursuers had not proved on the balance of probabilities that the cause of the failure was insufficient tightening of the nut. In that connection they could not succeed unless Mrs Wasserman's opinion evidence as to the cause was accepted. It ought not to be. It was without any sound foundation. It depended upon her assumption that at the time the connection was made on 17 November water pressure was low, and that it remained that way until shortly before the leak but then rose. There was no evidence of water pressure readings over the relevant period. Readings over a five day period the following month provided no support for the theory. Even if, despite that, one assumed the unlikely scenario that pressure on 17 November had been at the sort of level noted by Dr Graham (on 7 October the following year) (2.4 bar) but had risen to around 5 bar just before 30 November, it was clear from Dr Graham's test results that a connection which was tightened so as to be leak-free on 17 November would have required a water pressure of 11 bar to separate. Mr Graham's results had been accepted by Mrs Wasserman. He had been a more satisfactory and persuasive witness than she had. There was no discrepancy between his evidence at 6.11 and 7.13 of his report. They were dealing with different scenarios. At 6.11 the reserve pressure being overcome was 8 bar. In 7.13 the reserve pressure was 15 bar. Not only did Mrs Wasserman's theory not stack up, it was plain the possibility of the failure having been caused by the application of external force could not properly be excluded. More than that, it was a much likelier scenario than that posited by Mrs Wasserman. As Dr Graham's test results showed, Mr Hopkins' evidence had been predicated on his erroneous assumption that if it had been properly tightened the brass olive would have been deformed. The fact that in photograph 6/17/2 the nut securing the return valve to the copper pipe appeared to have been turned more than the nut over the olive and spigot did not indicate that the latter nut was under-tightened.

[65] Whoever connected the fitting it had not been shown that they failed to exercise the ordinary skill and care of a reasonably competent installer. There was no evidence from anyone qualified to speak to the standard of care to be expected of such a person. Mrs Wasserman wasn't qualified to give that evidence. In any event she had been unable to give clear evidence as to how far the nut should be turned where it was securing a brass spigot. Such evidence as there was indicated that ordinary practice would be to tighten to finger tight, tighten a little more using a spanner, and check it was leak-tight. If not, it would be tightened a little more until it was leak-tight.

[66] As to who made the connection the evidence of Mr McFarlane and Mr Feeney should be accepted in preference to that of Mr Noon and Mrs Gardiner. Mrs Gardiner's evidence had been demonstrably erroneous in several respects. While the evidence of McFarlane and Feeney did not dovetail it did provide confirmation and support of their account on the material matters. I should find them to be credible and reliable on those matters.

[67] If Mr Noon made the connection and if, contrary to the first defenders' submissions, the failure of the connection was caused through the first defenders' breach of contract/negligence and the second defender's negligence, liability should be apportioned 75% to the second defender and 25% to the first defender.

The second defenders' submissions
[68] Miss Shand moved for the second defenders to be assoilzied. She urged me to accept the evidence of Mr Noon that he had not made the connection, and to accept Mrs Gardiner's evidence in relation to that matter. The evidence of Mr McFarlane and Mr Feeney as to who had made the connection was contradictory. I should find their evidence on that matter to be incredible, or at least unreliable. Even if I was satisfied that Mr Noon made the connection the pursuers had not established that he was in breach of any duties incumbent upon him, nor was it established that the cause of the failure of the connection had been any such breach of duty. Undaunted by the absence of any record, or any raising of the issue during the proof, Miss Shand submitted that it had not been demonstrated that Mr Noon was acting in the course of his employment if and when he made the connection. Reference was made to Wilson v Excel UK Ltd 2010 SLT 671. Mr Di Rollo's submissions in relation to the cause of the failure were adopted. When considering the cause of the failure the court should bear in mind that the defenders had been prejudiced by the non-availability for expert examination of the olive, spigot and nut: Scottish & Universal Newspapers Ltd v Gherson's Trustees, supra, per Lord President Emslie at p. 48. If, contrary to her submissions, the second defenders were liable, the first defenders ought to bear the major responsibility. They were the persons with whom the pursuers had contracted to carry out the work. Their employees ought not to have allowed Mr Noon to make the connection - particularly as they had no knowledge of his experience or qualifications. An appropriate apportionment of liability would be 75% to the first defenders and 25% to the second defenders.

Vicarious liability and Mr Noon - the pursuers' response
[69] Mr Duncan contented himself by observing that not only was Miss Shand's suggestion that Mr Noon was acting outwith the course of his employment not one that was open to her on the pleadings or on the evidence, it also flew in the face of the modern authorities on the subject from Lister v Hesley Hall [2002] 1 A.C. 215 onwards.

Mr Di Rollo's objection
[70] There was no real dispute as to the relevant principles to be applied: Scottish & Universal Newspapers Ltd v Gherson's Trustees, supra; Peacock Group plc v Railston Ltd, supra; Haddow v Glasgow City Council, supra; Stirling Aquatic Technology Ltd v Farmocean AB (No. 2), supra.

[71] There is no doubt that the spigot, olive and nut were not made available for examination by the defenders. I accept the evidence of Mr McFarlane that he re-used them and that they remained in the coffee machine after he left on 30 November 2009.

[72] In my opinion the pursuers can be criticised for not taking immediate and appropriate steps to preserve the evidence. They knew they were dealing with a major incident. They knew or ought to have known that retaining the parts involved was important - Mr Topping appreciated that. At the time the non-return valve was produced it was incumbent upon them to clarify and locate the whereabouts of the other parts, and to secure their retention. Those obvious steps were not taken. Had they been it would have become apparent to them that the parts were still in their possession and control - within the machine.

[73] Have the defenders been prejudiced by that failure? They are not in a position to contest that the olive was not deformed or that it moved easily on the spigot. Had they had the original parts they might have been. Of course, Dr Graham has been able to demonstrate that even if the olive had those characteristics they were not demonstrative of insufficient tightening, so the evidence of lack of deformity and ease of movement is not compelling. Nonetheless, the objection to the admissibility of secondary evidence as to the state of the olive appears to me to be well founded.

[74] Mr Duncan appreciated the difficulty which he faced in this regard. He made clear that he did not seek to rely on Mr Hopkins' evidence as to the condition of the olive and the fact that it could be replaced on the spigot with ease. However he did rely on Mr Hopkins' evidence that when he untightened the nut it was not as tight as he had expected it to be. He submitted that that point was a separate one, distinct from Mr Hopkins' evidence about the lack of deformity in, and ease of movement of, the olive. I disagree. In cross-examination Mr Hopkins clarified that his conclusion that the nut had been insufficiently tightened was based upon his belief that with a properly tightened nut the olive would have deformed.

[75] Notwithstanding Mr Duncan's concession, the proper course appears to me to be to sustain Mr Di Rollo's objection. The consequence is that Mr Hopkins' evidence as to the state of the olive, and Mrs Wasserman's comments thereon, are inadmissible secondary evidence.

[76] The inability to comment on the deformity or otherwise of the olive was not the only prejudice said to have been caused by the non-availability of the parts. Dr Graham indicated that had he had the parts he would have examined them microscopically. Markings on them might have been of assistance in determining how tightly the connection was made. Mrs Wasserman accepted that it would have been helpful to have had the parts. Although she was sceptical as to the likelihood of worthwhile evidence being available after two subsequent tightenings, she recognised that having the spigot could have been useful if there had been more than one set of marks on it. That might show it had been differently inserted on different occasions. I shall return to the question of prejudice later.

Who made the connection?
[77] I accept the evidence of Mr Noon that he did not make the connection and that it was made by one or other of Mr McFarlane or Mr Feeney. Mr Noon gave his evidence in a straightforward manner. His evidence was not undermined during cross-examination. I found him to be a credible and reliable witness. I draw support for his account from the evidence of Mrs Gardiner and from Mr Aird's evidence as to the fact that when photographed the day before the pipe had been capped and did not have a non-return valve on it.

[78] By contrast neither Mr McFarlane nor Mr Feeney were impressive witnesses when it came to recounting what took place in the lead-up to, and the making of, the connection. There were numerous inconsistencies between their respective accounts, and between their accounts and the evidence of Mr Noon and Mrs Gardiner. While my impression was that Mr Feeney was genuinely trying to answer questions to the best of his recollection, I was not persuaded that his recollection of these aspects was at all good or accurate. It is possible that both he and Mr McFarlane have convinced themselves that the connection was indeed made by Mr Noon, but whether that be so or not I reject their evidence on the issue as being unreliable. Further, I do not accept that the non-return valve was pre-fitted.

The cause of the leak
[79] I accept that the joint was leak-free at the time of installation - the evidence in relation to that (from Mr Noon, Mr McFarlane and Mr Feeney) was all one way. It remained leak-free until shortly before the failure.

[80] Mrs Wasserman had the disadvantage of having been instructed late in the day. She did her best to assist the court, but I did not find her evidence on the contentious matters to be persuasive. Her opinion was based, in part, upon inadmissible evidence (though she maintained that even without it she stood by her opinion). Even had I not ruled that evidence to be inadmissible, I would not have accepted that it had the significance which Mr Hopkins and Mrs Wasserman appeared to attach to it. In that connection I accept Dr Graham's findings that, even where tightening was such that the instantaneous failure rate of the connection far exceeded any water pressure which the joint could reasonably have been expected to be exposed to, the olive appeared to remain undistorted.

[81] Mrs Wasserman considered two possible causes - insufficient tightening and the inadvertent application of external force to the connection. She had not been not been asked to consider the deliberate application of external force (vandalism). She accepted that the absence of any reported leaks over the lengthy period between installation and 30 November indicated that the joint was sufficiently tight to be leak-free during that period.

[82] In my opinion the scenario favoured by Mrs Wasserman is conjectural. There is no evidence as to what the water pressure was at the time of installation. There is no evidence as to the water pressure level or levels between that time and the time of the failure. Her theory requires a supposition to be made that the water pressure range at the material times was 2.4 bar to 5.7 bar. More than that, it involves the following assumptions: (i) that the relevant water pressure level at the time of installation was 2.4 bar; (ii) that the degree of tightening was insufficient, but just sufficient to make it leak-free at around that pressure; and (iii) that it continued at about that pressure until very shortly before the failure, when pressure rose significantly causing the failure.

[83] Even without Dr Graham's test results I would have found it impossible to hold that the scenario suggested by Mrs Wasserman was established on the balance of probabilities. The application of external force appears to me to provide a much more plausible, and a more likely, explanation of the failure. In that regard it was not without significance that when Mrs Wasserman prepared her report she proceeded on an assumption that the level of activity in the building was lower than it in fact was. Once regard is had to Dr Graham's test results Mrs Wasserman's theory appears even more untenable.

[84] I turn then to Dr Graham's evidence. He was an impressive witness. His evidence was clear and his reasoning was cogent. He has considerable experience in dealing with compression joint failures - more experience in that regard than Mrs Wasserman. His report was thorough. His test results were accepted by Mrs Wasserman. He was able to explain his results and his reasoning, and was both logical and persuasive. I accept his evidence.

[85] In order to be sufficiently tightened to be leak-free at a water pressure of even 2.4 bar the joint would have had an instantaneous failure pressure of about 11 bar. There was no evidence of water pressure ever being that high. The pressure at the local main when it was monitored over a five day period in December 2009 was around 5 bar, and when Dr Graham visited on 7 October 2010 water pressure in the branch pipe upstream of the joint was 2.4 bar with a telltale indicating that at some time in the past it had reached 5.7 bar.

[86] I agree with Dr Graham that a likelier explanation for failure of the connection (than the scenario suggested by Mrs Wasserman) is the application of external force - inadvertent or deliberate. The examples he gave of how the requisite level of force might have been applied inadvertently - by movement of the machine or by force being applied directly to the hose - are entirely plausible. So far as the inadvertent application of force was concerned, I do not accept that the person responsible would have been bound to have noticed leaking and done something about it. The application of force may not have caused immediate failure. A joint could become mobile at a pressure about 80% below the instantaneous failure point, with failure following later. Further, even if a person responsible for exerting force had become aware of the problem, it is not a given that he or she would have admitted to what they had done.

[87] I do not accept that there is any inconsistency between paragraphs 6.11 and 7.13 of Dr Graham's report. In paragraph 6.11 the "firm pull" was applied in circumstances where the water pressure had been increased to 12 bar. The reserve force was only 8 bar. In 7.13 the scenario was that the reserve force to be overcome was 15 bar (20 bar minus 5 bar).

[88] I do not consider that the evidence about photograph 6/17/2 is worthy of much weight. It was not a matter Mrs Wasserman thought important enough to mention in her report. Dr Graham noted it in his report and referred to it in his evidence but it did not impact upon his conclusions. Had there been evidence (i) that the nut on the copper pipe end of the non-return-valve had been turned no more than was necessary to be adequately tightened, and (ii) that the tightness of both nuts ought to have been the same, it might have been more significant. There was no such evidence.

[89] It is not necessary for me to find, or for the defenders to establish, what the cause of the failure was. It is for the pursuers to show that it was caused in the way they aver. In my opinion the evidence falls far short of establishing on the balance of probabilities that the failure was caused in the way Mrs Wasserman suggests. Not only do I consider Mrs Wasserman to have been wrong to exclude the application of external force as a possible cause: on the evidence that appears to me to be a more likely explanation than the one she puts forward. I reach that conclusion without having had to resort to viewing the pursuers' case more cautiously or carefully than might otherwise have been necessary had the missing parts been preserved (cf. Scottish & Universal Newspapers Ltd v Gherson's Trustees, supra, per Lord President Emslie at p. 48; Stirling Aquatic Technology Ltd v Farmocean AB (No. 2), supra, per Lord Johnston at p. 456L). Nonetheless, had matters been less clear cut, in my view the potential prejudice to the defenders caused by the non-preservation of the parts would have provided good reason for exercising caution before accepting that the pursuers' case was proved.

[90] The circumstances of the present case are readily distinguishable from those in Drake v Harbour, supra. In that case the court held it to be clearly established that the defendants had been negligent. The damage which had occurred was the kind of damage which was likely to have resulted from their negligence. The trial judge had held the other suggested explanations were improbable. On those facts it was held on appeal that he had been entitled to infer that the damage was caused by the negligence even though the claimant was unable to prove positively the precise mechanism. By contrast, here the very evidence which is relied upon by the pursuers to establish causation is also the crucial evidence from which they ask the court to draw the inference of negligence: and, far from there being no credible alternative explanation of how the failure was caused, the alternative explanation is more plausible.

Did the first defenders' employees fail to exercise the care expected of installers of ordinary competence?
[91] How tightly would such installers have made the nut? In her report the degree of turn past finger tight which Mrs Wasserman mentions ( is a quarter turn. In examination-in-chief she initially suggested somewhere between three-quarters of a turn to one and a quarter turn past finger tightness. In cross-examination she said her understanding of the recommended approach to tightening was to tighten to about half a turn to three-quarters of a turn past finger tight, and if the joint still leaked to tighten a little bit more. That seemed more consistent with the other evidence. Mr Feeney said that if he had been doing the task he would have turned the nut a half turn past finger tight, or slightly more, and made sure it was watertight. Mr McFarlane suggested he might have turned it about a three-quarter turn past finger tight. Both Mr Feeney and Mr McFarlane were very experienced installers. It is clear from Dr Graham's evidence that tightening a half turn past finger tight would not have involved applying a torque lower than that recommended by the manufacturers. Checking for leaks after tightening would have been in accordance with their guidance. Had the evidence been that the nut had indeed been tightened to about half a turn past finger tight and that the joint had been found to be leak-free in my opinion there would have been no proper basis for holding that the installation had been negligent.

[92] The fact is that there is no direct evidence of how far the nut was turned. There is clear evidence that on checking the joint after installation it was leak-free. There is no evidence of there having been any leak until shortly before the flood was discovered. The evidence upon which the pursuers rely to justify the inference of negligence is essentially the same evidence upon which they rely to prove causation. In my opinion they have failed to prove on the balance of probabilities (i) that the failure was caused in the way they suggest, or (ii) that the installation of the joint was carried out negligently.

Vicarious liability of Mr Noon and apportionment of liability between the defenders
[93] Since the pursuers have failed to establish liability against either of the defenders the issues of the second defenders' vicarious liability for Mr Noon, and the appropriate apportionment of liability between the defenders, do not arise.

[94] Had it been established that Mr Noon made the connection, that he was negligent in doing so, and that that was the cause of its failure, I would have had no difficulty in holding that the second defenders' were vicariously liable for his negligence. I would have rejected the proposition that Mr Noon was engaged on a frolic of his own. The context was that he had attended to represent his employers at the request of the pursuers. His employers had installed the pipework. He regarded it as his responsibility to bring a fitting which might be needed to make the connection between the machine and the pipe ("it was possible the final connection wasn't correct"). His evidence was that while he hadn't made the connection between the hose and the pipe, "If I had had to I would have." He also regarded it as being part of his responsibility to check that the connection for the coffee machine was leak-free once it had been installed. Applying the principles discussed in Lister v Hesley Hall, supra and Wilson v Excel UK Ltd, supra I have no hesitation in concluding that had Mr Noon connected the joint he would have been doing something which was closely connected with the duties he was authorised by his employers to perform; and that it would have been fair and reasonable to hold the second defenders vicariously liable. In that event I would have apportioned liability equally inter se the defenders. Among the factors which would have weighed in the balance are (i) the second defenders' employee would have been the person who failed to tighten the nut adequately; (ii) the first defenders would have been in breach of their contract with the pursuers; (iii) Mr Noon had been presented to the first defenders' employees by Mrs Gardiner as being the person responsible for the pipework: in those circumstances it would not have been unreasonable for them to assume that he was competent to make the connection.

Conclusion and disposal
[95] The pursuers have failed to prove the case against either defender. I shall repel the first and second pleas-in-law for the pursuers, sustain the second and third pleas-in-law for each of the defenders, and pronounce decree of absolvitor. I shall reserve meantime all questions of expenses.