EXTRA DIVISION, INNER HOUSE, COURT OF SESSION
Lord Eassie Lord Menzies Lord Brodie	[2013] CSIH 41 P188/11 OPINION OF THE COURT delivered by LORD MENZIES in the petition of by PAUL BOVA and CAROL CHRISTIE Petitioners and Reclaimers; against THE HIGHLAND COUNCIL Respondents: and BDW EAST SCOTLAND LIMITED Interested Party _______________

Act: Drummond, QC, Findlay; Drummond Miller LLP

Alt: Thomson, QC, McKay; Biggart Baillie LLP

Interested Party: Martin, QC, Burnet; Maclay Murray & Spens LLP

3 May 2013

Introduction

[1] In early 2009 the interested party applied to the respondents for planning permission to erect 64 houses and associated roads, car parking and below ground services on land at Resaurie, near Inverness. The petitioners are joint owners and occupiers of a house known as "Barnview" which is situated to the south west of the area of land which the interested party wished to develop. By letters dated 20 April and 1 May 2009 the petitioners objected to the application for planning permission. The relevant committee of the respondents resolved to grant the application on 23 September 2009, subject inter alia to a section 75 Agreement being entered into in relation to the provision of affordable housing. The section 75 Agreement was finalised on 22 February and 2 March 2010. On 5 March 2010 the respondents granted planning permission to the interested party for the proposed development.

[2] On 24 February 2011 the petitioners raised the present proceedings for judicial review of the respondents' decision of 5 March 2010. The petition was opposed by the respondents and by the interested party, and the matter came before the Lord Ordinary for a first hearing. The petitioners sought declarator that the decision of 5 March 2010 was ultra vires, and reduction of it. The petitioners argued before the Lord Ordinary that the respondents had failed to understand and take proper account of the petitioners' objections relating to the risk of flooding caused by the likely effects of the development on groundwater on the site, and also that the respondents had failed to adopt a precautionary approach to flood risk, as they ought to have done. Both the respondents and the interested party opposed these contentions, and further argued that the petition had been brought too late and that the petitioners were barred by mora, taciturnity and acquiescence from pursuing it.

[3] By interlocutor dated 19 August 2011 the Lord Ordinary repelled the petitioners' plea-in-law, sustained certain of the pleas-in-law for the respondents and the interested party, and refused the petition. Against that interlocutor the petitioners have now reclaimed. The submissions advanced on behalf of the petitioners before us may be summarised in the following two propositions:-

(1) In reaching their decision dated 5 March 2010, the respondents failed to have regard to a material consideration, namely the increased risk of ground water flooding to the petitioners' property and other properties on the southwest boundary of the site.

(2) Further, the respondents failed to have regard to another material consideration, being a change of planning policy (in the interval between the resolution to grant consent and the formal grant) which introduced a requirement to take a precautionary approach to flood risk.

[4] Both the respondents and the interested party opposed these contentions before us. In addition, the interested party maintained their position that the petition had been brought too late, and that the petitioners were barred by mora, taciturnity and acquiescence from pursuing it. Furthermore, both the respondents and the interested party argued that even if the court were persuaded that either of the above propositions was made out, it should nonetheless exercise its discretion to refuse the remedy sought - a significant time had elapsed since the grant of planning permission, the petitioners had made no application for interim suspension or interim interdict, 13 houses had already been nearly completed and foundations for 20 other houses had been installed, and access roads had been constructed. The utility and practical results of quashing the respondents' decision were questionable.

[5] Each of the parties produced very full and helpful written submissions in support of the respective positions which they adopted before us. We have taken into account everything submitted to us both in writing and orally, but we do not consider that it is necessary to repeat all these submissions at length.

Issue (1):

The consideration given by the respondents to the risk of ground water flooding to the petitioners' property and other properties on the southwest boundary of the site.

[6] Issues of groundwater and flooding were raised in several documents which were before the respondents before they granted planning permission. A Geo-Environmental Desk Study Report prepared on the instructions of the interested party by WA Fairhurst & Partners ("Fairhurst") dated 10 May 2007 was the earliest document available. The sources of information which were utilised in preparation of the report were listed at para 2.0 of the report; these included ordinance survey maps from 1871 to 2004, and three British Geological Survey sheets, namely (1) the Hydro-Geological Map of Scotland dated 1988, (2) the Groundwater Vulnerability Map of Scotland dated 1995 and (3) Scotland Sheet 84W Fortrose Solid and Drift Edition dated 1997. Other sources of information included a consultation with the respondents, a site walkover, and a search of a SEPA website "Indicative River and Coastal Flood Map of Scotland". Section 5 of the report dealt with geology and hydro-geology, and contained the following information at para 5.3:

"Hydrogeology

The BGS Groundwater Vulnerability Map of Scotland indicates the bedrock beneath the site is moderately permeable. The Hydro-Geological Map of Scotland indicates the bedrock beneath the site is a locally important aquifer of lower and middle Old Red Sandstone in which flow is dominantly in fissures and other discontinuities.

The Groundwater Vulnerability Map supplied with the Enviro-Check Report indicates that the strata beneath the site are moderately permeable fractured or potentially fractured rocks which do not have a high primary permeability. Based on the general topography of the area and flow of local surface water courses, it is anticipated that the groundwater flow will be to the NW."

[7] Section 7 of the report gave a preliminary engineering design assessment, which included the following passage:

"Two marshy areas have also been identified at the southern and northern corners of the site. These areas will require further investigation, particularly in the south as the marshy area corresponds to the approximate position of a historical well on the southern site boundary.

The proposed development plan does not appear to take account of the existing pond on site, however this will obviously impact on the final layout."

In its summary and conclusions, the report noted that "it is also considered that there is a significant risk of geo-technical difficulties associated with the made ground and marshy areas at the site."

[8] The second document which was available to the respondents was a Geo-Environmental Interpretative Report prepared by Fairhurst dated 24 July 2007. Para 2.2 of this report dealt with the published geological information and stated that "based on the general topography of the area and flow of local surface water courses, it is anticipated that groundwater flow will be to the north west."

[9] The next document which was before the respondents was a Drainage Impact Assessment and SUDS (sustainable urban drainage systems) Strategy revised as at 15 August 2008 (and again on 17 April 2009). This made reference to the Geo-Environmental Report and noted that the site investigation(which had included sinking boreholes to 7 metres and pits to 3 metres below ground level) did raise the issue of high water-table levels across the site, generally found to be 0.5m to 1.9m below existing ground levels. The rainwater SUDS strategy set out in the report considered on site post-development drainage and offsite post-development drainage. With regard to the first of these, it was calculated that post-development outflows from the site would be less than pre-development flows. With regard to the second, as a result of a separate surface water drainage management system, attenuation was to be provided to limit the post-development flows from the off-site water courses to less than calculated pre-development flows. It noted that it was likely that ponding in the area of Water Course No 2 was as a result of rising ground waters, and made proposals to deal with this.

[10] The respondents' officers were aware of the concerns of local residents, including those on the south west boundary of the site such as the petitioners, about the risk of flooding if the development proceeded. On 19 August 2008 Mr Keith Gibson, the respondents' area planning and building standards officer, sent an email to his colleague Mr McKenzie in TEC Services. This included the following passage:

"As the neighbours on the southwest boundary are particularly concerned about SUDS and flooding Dave has asked if you could confirm your views on the revised proposals if that's possible by email? In particular, he would appreciate any summary you can give on water coming off the hill near Phase 1 which is of concern to neighbours."

[11] Mr McKenzie responded to this by email dated 21 August 2008. He indicated that he could accept the figures provided and that no dwelling would be detrimentally affected, and he supported the approach of the developer's engineers.

[12] By letter dated 20 April 2009 ("the first letter") the petitioners wrote to the respondents objecting to the interested party's proposal to develop the site. In this letter the petitioners listed several grounds of objection to the development proposals, including density, contamination, subsidence, European protected species (bats), material change of use and design statement. The fourth ground of objection was flood alleviation and surface water proposals. Under this heading, the petitioners' objection was as follows:

"Again, your attention is drawn to Committee Meeting on 2 December 2008 where members noted their concern surrounding the fact that the above site floods regularly. No drainage assessment is included within the information presented - as such a material breach of PAN 61. There are no source control measures proposed, no source identification, no SUDS proposals. No assessment of water quantities which inundate the site each winter - despite the applicants having had a full winter to conduct such a survey, and such a survey previously expressly intended by the applicant - we object to any such development."

[13] By letter dated 1 May 2009 ("the second letter") the petitioners wrote again to the respondents objecting to the proposed development. This letter included the following passages:

"WA Fairhurst state to have completed a full geo-environmental site investigation in summer 2007 and noted a high water table between 0.5m and 1.9m. WA Fairhurst state in submitted 2009 drainage assessment to assume the ponds on site, discharge from site beneath Tower Brae Burn.

Considering the well-documented drainage concerns surrounding this development, residents in Cranmore Drive will no doubt be less than impressed being presented with assumptions having been flooded twice and living in houses with no home insurance:-

As stated by WA Fairhurst, there is a high, uneven water table with limited and undefined discharge from site. If we consider the evidence of these ponds and the high water table clearly not being horizontal, this suggests to us, an aquifer is present on site.

Within an aquifer, the water table is rarely horizontal, due to the existence of surface relief, resulting from the capillary effect within the porous media.

Considering these facts, alongside the limited, undefined migration from site, particularly the fact that the site can remain bogged while the burn remains relatively dry and water pools are evident on Ashton Farm land below approx 50% of the site. We question the utilisation of green field runoff figures to establish target discharge values. ...

What is being proposed may purport to improve the drainage of the site, however, may actually re-direct natural migration of ground water recharge occurring in other areas which have no direct impact on the burn, with some hostility, into Tower Brae Burn. Indeed it is of little reassurance to residents that Area roads have failed to offer any comment on this subject during 2008, despite being lead body for flood risk.

We object to the drainage assessment submitted, which appears to breach SSP 7, paragraphs 15, 16, 17, 22, 25 and PAN 61, paragraphs 23 + 24."

It is to be noted that the Tower Brae Burn and Cranmore Drive lie to the north of the site, on the opposite side from Barnview.

[14] The Scottish Environment Protection Agency ("SEPA") provided its consultation response to the respondents in respect of the proposed development on 20 May 2009. SEPA had no objection to the proposed development, subject to a planning condition being imposed in terms similar to the following:

"A detailed Drainage Design should be submitted and approved by Highland Council (in consultation with SEPA if deemed necessary by the Council) prior to development commencing. Post-development runoff from the site should not exceed the pre-development runoff rates for all return periods up to and including the one in 200 year storm event. The Drainage Design should include a sensitivity test showing that no built development or critical infrastructure would be affected by flooding during a one in 200 year storm event to satisfy SPP 7 requirements."

[15] SEPA supported the proposal made by the interested party that inflows onto the site from elsewhere should be monitored during the winter period after which appropriate sized attenuation facilities should be designed to prevent increased flood risk elsewhere, and indicated that this monitoring should be undertaken prior to finalising the detailed drainage design. SEPA also noted that the outflow rate from the proposed detention basin will be restricted by a flow control device to ensure that flooding would not be increased elsewhere, and that this could offer betterment on the existing drainage situation provided that it is appropriately sized and outflow-controlled.

[16] The respondents' planning officer sent a copy of the petitioners' second letter to the architects acting on behalf of the interested party for their comments, and this was passed to Fairhurst. By letter dated 3 July 2009 Fairhurst wrote to the planning officer commenting on the relevant representations. With regard to issues of drainage and site specific issues, Fairhurst observed inter alia as follows:

"With regards comments that there has been historical flooded to the immediate area in the recent past, WA Fairhurst & Partners have had it confirmed by Highland Council TEC Services that this flooding was as a direct result of the road culvert in Tower Brae Burn becoming blocked with debris. This culvert has now been completely replaced to minimise the risk of debris blockage, therefore flooding.

With regards the flow monitoring for the 'off-site' drainage, this will commence as soon as any Planning Permission has been granted for the development. As discussed above, these works are to be conditioned on any planning approval document, at the request of SEPA and TEC Services. These monitoring works will have to be undertaken to fully design out the SUDS strategy for the 'off-site' drainage and submitted for approval to both statutory authorities, prior to any works proceeding on site.

With regards the statement that an aquifer may be present on site, WA Fairhurst & Partners would suggest these facts are unfounded as there is no evidence of an aquifer present both from onsite inspections or within the site investigation studies. In any case, the development will result in only the shallow sub-soils being affected, any aquifer would be at a depth that the development works would not affect."

[17] The planning application came before the Inverness, Nairn, Badenoch and Strathspey Planning Applications Committee on 11 August 2009. The planning officer had prepared a report which was before the Committee, with a recommendation that planning permission should be granted subject to conclusion of a Section 75 Agreement and obtaining any necessary bat licence. The report summarised the main concerns of the objectors, the first of which was flooding. It summarised the position adopted by the various consultees, including SEPA (which agency later confirmed by letter dated 24 August 2009 that the report "very accurately" reflected its position on the application and that the terms of the proposed conditions exactly addressed the issues which SEPA had asked to be covered by means of a condition). At para 6.3 the report considered drainage and site specific issues, and repeated the substance of Fairhurst's observation about an aquifer contained in the letter dated 3 July 2009. Part 7 of the report gave the planning officer's planning appraisal of the proposal, and considered drainage issues at para 7.7 to 7.9 Concerns about flooding and surface water were considered at para 7.14. The planning officer recommended the grant of planning permission subject to 25 conditions; Proposed Conditions 10 and 11 related respectively to surface water disposal arrangements and a detailed drainage design approved by the planning authority in consultation with SEPA. Proposed Condition 23, with its supporting reason, was in the following terms:

"23. Unless otherwise approved in writing with the Planning Authority, no works shall start on site until an application has been submitted for the details of the proposed works adjacent to the south boundary and the culvert for Phase 1 to accommodate attenuation for the surface/ground water from this direction to the satisfaction of the Planning Authority in consultation with SEPA.

Reason: In the interests of amenity and to ensure water surface/ground water from outwith the application site is dealt with in terms of SUDS principles."

At the Committee's meeting on 11 August 2009 the application was approved subject to conclusion of an agreement on provision of affordable housing.

[18] In terms of the respondents' standing orders, a review of the decision of the Committee of 11 August 2009 was held at the Planning, Environment and Development Committee of the respondents on 23 September 2009. The planning officer recommended the application for approval, and drew the attention of the Committee to certain points within his report, including the proposed conditions to address problems of flooding, and that the respondents' Transport, Environmental and Community Services Committee, SEPA and Scottish Natural Heritage had each been provided with a copy of the report and had each confirmed that they were content with the proposals and conditions. There followed a discussion about the concerns of local residents, which included a concern about flooding. In response, the planning officer explained that the proposals were designed to ameliorate the existing flooding problems and the outcome should be an overall improvement. It was his view that should the Committee decide to refuse the application on the grounds of flooding, this would not withstand challenge. The Committee agreed to uphold the earlier decision of 11 August 2009 to approve planning permission subject to conditions as set out in the report and a footpath being provided. By letter dated 5 March 2010 the respondents granted planning permission subject to conditions, which included conditions in the same terms as the Proposed Conditions 10, 11 and 23 noted above.

[19] In response to the requirement to provide a detailed drainage design and surface water disposal arrangements, in May 2011 Fairhurst provided a Hydrometric Survey, Ground Water Flood Attenuation Assessment and Drainage/SUDS proposals. This considered the existing conditions at section 2, which noted that it was likely that flood water within the detention area and the pond were caused by a combination of direct runoff, flows from the culvert under the railway line (to the south of the site) and raised ground water levels. Section 3 concerned the hydrometric survey and ground water monitoring, and concluded that water levels within the detention area were influenced by other facts such as ground water levels. Section 4 dealt with the proposed development and mitigation measures. It noted as follows:

"During raised ground water conditions where water levels in the permanent pond and the detention area exceed the natural spill levels flood water flows over land towards the water course. The proposed housing development obstructs these overland flows and therefore the low lying area at the south west end of the site is to be re-profiled to maximise the volume of attenuation provided. New outlet control arrangements are to be provided to maintain the existing low flow discharge rate and the higher capacity overland flow rate... The volume of active storage provided within the reprofiled detention area provides a significant increase over the existing conditions based on a level for level scenario."

[20] Section 5 of the assessment and proposals gave Fairhurst's conclusions, which included the following:

"The volume of attenuation provided based on the reprofiled detention area exceeds that of the current arrangement based on a level for level scenario and therefore has the ability to attenuate a greater volume of water.

The low flow outlet arrangement has been designed to attenuate flows to 0.5l/s up to water level reaching a level of 46.3mAOD in line with current arrangement. This ensures that ground water flows from this area entering the water course do not exceed those based on the current scenario...

Under current arrangement ground water cannot spill away from the detention area until water levels exceed a level of 46.8mAOD. Lowering this to 46.4mAOD together with the provision of additional volume of open attenuation will increase the standard of protection provided to the existing surrounding properties... The above measures ensure that the probability of flooding away from the development is not increased and that the development itself is appropriately protected from flooding in line with SPP."

[21] We record that in addition to the above material, some reference was made before us to a supplemental expert report dated 27 June 2011 prepared by Jackson Consulting on the instructions of the petitioners. This report was of course not before the respondents when they made their decision to grant planning permission subject to conditions in September 2009, nor was it available to them when planning permission was ultimately issued in March 2010. This report was critical of the approach adopted by Fairhurst, and that adopted by the respondents. Counsel for the petitioners made brief reference to this report in order to show that the petitioners concerns had some basis and were not fanciful.

[22] Before the Lord Ordinary, the petitioners submitted that the respondents had failed to have regard to a material consideration, namely the concerns expressed in the second letter relating to the risk of flooding, particularly as a result of the effect of the development on groundwater flows. The Lord Ordinary considered these submissions at paragraphs [37] to [46] of his Opinion. He was not persuaded that the respondents failed to give adequate consideration to any of the objections taken by the petitioners.

[23] Before us, it was argued for the petitioners that both Fairhurst and the respondents' planning officer (and so the respondents themselves) failed to understand the potential significance of an aquifer, and the effect which the proposed development might have on groundwater flows and potential flooding to properties outwith the site. It was submitted that a failure to appreciate the complex hydro-geology of the site and its surrounding area lay at the heart of the petitioners' complaint, and that this failure amounted to a failure to have regard to a material consideration. This was an error of law which justified the setting aside of the decision. The Town & Country Planning (Scotland) Act 1997, section 37(2) required the respondents to have regard to the provisions of the development plan, so far as material to the application, and to any other material considerations. Reference was made to Wordie Property Co Ltd v Secretary of State for Scotland 1984 SLT 345, Tesco Stores Ltd v Secretary of State for the Environment [1995] 1 WLR 759; Oxton Farms and Samuel Smith Old Brewery (Tadcaster) v Selby District Council and Perisimmon Homes (Yorkshire) Ltd [1997] EWCA Civ 4004; (1997) EG 60; and R v Durham County Council ex p Lowther [2002] 1 P. & C.R. 22.

[24] In the present case, albeit unwittingly, the respondents' planning officer misled the Committee about the presence of an aquifer. If the presence of an aquifer was a material consideration, the Committee took its decision without having regard to this. This was clearly potentially capable of affecting the result, which was all that the petitioners had to show. As Lord Keith of Kinkel observed in Tesco Stores (at 764G):

"It is for the courts, if the matter is brought before them, to decide what is a relevant consideration. If the decision maker wrongly takes the view that some consideration is not relevant, and therefore has no regard to it, his decision cannot stand and he must be required to think again."

As Pill LJ observed in Lowther (at paragraph 98), the duty of a planning officer in reporting to a Committee is broader than a duty not actively to mislead. It includes a positive duty to provide sufficient information and guidance to enable the members to reach a decision applying the relevant statutory criteria. In the end, it is a matter of fact and degree for the members.

[25] Although the respondents claim that they did consider the importance of raised groundwater levels and the risk of groundwater flooding, there was really no assessment of the risk of flooding from onsite groundwater in any of the reports before them. Conditions 10 and 11 attached to the grant of planning permission dealt only with surface water, and Condition 23 was concerned with offsite surface and groundwater coming onto the site. Although bore holes were dug and measurements showed a high and uneven water table, no measurements were taken of the direction or speed of flow, and there was merely an assumption that the flow would be towards the northwest of the site. Given the topographical features of the site, the existence of an aquifer, the presence of ponds and wells, and an uneven water table, such measurements ought to have been taken, and the issue ought to have been highlighted to the respondents' Committee. The Lord Ordinary observed (at the end of paragraph [38] of his Opinion) that it was clear that Fairhurst certainly had not ignored the question of groundwater in their consideration of matters. The petitioners did not suggest that Fairhurst had ignored it completely, but they failed to assess the risk of flooding from groundwater on the site. They did not assess the source or flow of groundwater or what effect the development would have on this. Taking the first and second letters together, senior counsel for the petitioners submitted that it was clear that the petitioners had concerns not only about the effect of the development on the residents of Cranmore Drive, but about the presence of an aquifer, a high uneven water table, and redirection of natural migration of groundwater. The planning officer did not mention these concerns in his report to the Committee. Although the desk study report made reference to an aquifer, this was not picked up in the Geo-Environmental Interpretative Report. The drainage impact assessment and SUDS strategy did not assess the existence of an aquifer, nor the source of the groundwater nor the impact of the development on this. This was the heart of the petitioners' submission on this point. A mistake of fact giving rise to unfairness, which has played a material (not necessarily decisive) part in the Committee's reasoning, is sufficient to justify the decision being set aside - E v Secretary of State for the Home Department [2004] EWCA Civ 49, [2004] QB 1044. In the present case, how the presence of an aquifer interacts with groundwater on the site is unknown. The petitioners do not suggest that this will inevitably result in a risk of flooding, but it is a matter which must be investigated.

[26] Counsel for the respondents adopted their written submissions (No 35 of process) and began by advancing the seven propositions of general principles set out in paragraph 1 thereof. They may be summarised as follows:-

(i) A material consideration is one which is relevant to the determination of a planning application; it is for the court, if the matter is brought before it, to determine what is a relevant consideration, but the weight to be attached to a relevant consideration is entirely for the decision maker provided he does not act unreasonably (Tesco Stores).

(ii) A material consideration is a factor which has some weight in the decision making process, though it need not be determinative - R (on the Application of Kides) v South Cambridgeshire DC [2002] EWCA Civ 1370; [2003] 1 P & CR 19. It is a matter which gives rise to a real possibility that the decision maker would reach a different conclusion if he did take that consideration into account - Bolton Metropolitan Borough Council v Secretary of State for the Environment [1991] 61 P. & C.R. 343.

(iii) The correct interpretation of planning policy is an issue of law, reading the words used objectively in their proper context - Tesco Stores.

(iv) There are practical limits to the duty to have regard to material considerations. A planning authority does not fail in its duty to have regard to a material consideration, the existence of which it (or its officers) did not discover or anticipate and could not reasonably have discovered or anticipated. Where, prior to a decision notice being issued, a planning officer does become aware (or ought reasonably to have become aware) of a new material consideration the matter must be referred back to the Committee for reconsideration in light of the new consideration (Kides), but this must be done applying commonsense. If there is nothing new, and no reason for a rational planning committee to change its mind, it would be pointless to refer the matter back to the Committee - R (on the Application of Dry) v West Oxfordshire DC [2010] EWCA Civ 1143; [2011] 1 P. & C.R. 16.

(v) A planning officer's report to Committee should not be construed as if it were a statute. It is the overall fairness of the report which must be considered - Oxton Farms. The planning officer's duty is to provide sufficient information and guidance to enable the Planning Committee to reach a decision - Lowther. His expert judgment in assessing the matters to be brought to the attention of the Committee is entitled to some respect - R (Fabre) v Mendip DC (2000) 80 P. & C.R. 500; R (Miller) v North Yorkshire County Council [2009] EWHC 2172 (Admin).

(vi) Provided that all material considerations have been taken into account, the extent and quality of information required by a planning authority in order to enable it to assess and decide upon a planning application is a matter of planning judgment and entirely for the planning authority to determine - Simson v Aberdeenshire Council [2007] CSIH 10; 2007 SC 366.

(vii) If the court concludes that a material consideration was left out of account, and that the matter was either fundamental to the decision or there is a real possibility that consideration of the matter would have made a difference to the decision, the court may hold that the decision was not validly made - Bolton Metropolitan Borough Council.

[27] Against the background of these propositions, counsel for the respondents submitted that a normal and reasonable interpretation of the second letter was that it was concerned with water flowing towards Tower Brae Burn and Cranmore Drive, and not towards the petitioners' property.

[28] The possibility of an aquifer on or in the vicinity of the site was not a matter of particular or specific importance in relation to this proposal. The potential for an aquifer was noted in paragraph 5.3 of the Desk Study Report, but this was based only on the Hydro-Geological Map of Scotland. This map must be read as a whole, together with its explanatory notes, which state that it indicates aquifer potential in necessarily generalised terms. The site falls within an area which may have an aquifer dominantly in fissures and discontinuities in the bedrock of old red sandstone. Many of the major conurbations in Scotland, including Inverness, Dundee, Perth and parts of Edinburgh and Greater Glasgow, are built on similarly categorised land. It is wrong to draw the inference from this map that there is a locally important aquifer on a particular site - there is merely an indication of general potential. There is nothing to suggest that an aquifer may cause or contribute to groundwater flooding on this site. (The report by Jackson Consulting post-dated the respondents' decision, and was not relied on before the Lord Ordinary nor by senior counsel for the petitioners. The respondents do not accept the conclusions of that report, and the court should not rely on it.) There is nothing to suggest that there is an aquifer under this site, and in any event nothing to suggest that an aquifer would be potentially significant for this development proposal. The attenuation measures proposed by Fairhurst were designed to deal with all issues of rising groundwater (irrespective of its source). In essence, the professional opinion provided by Fairhurst to the respondents' planning officer was (a) there was no evidence of an aquifer on site, (b) if there is an aquifer on site it was at a depth such that the development will not affect it, and (c) in any event the attenuation measures were designed to cope with and improve the present groundwater situation. The report on groundwater flood attenuation assessment prepared by Fairhurst in May 2011 supports the view that these attenuation measures will be successful. The Lord Ordinary was correct in reaching the conclusion that all issues relating to flooding had been addressed, and there was nothing to support the argument that the potential for an aquifer was ignored, that the respondents had failed to take account of a material consideration, or that they had reached their decision under material error of fact.

[29] Counsel for the interested party submitted that the Lord Ordinary did not err in law in his construction of the first and second letters. His treatment of this ground of challenge, at paragraphs [37] to [39] of his Opinion, was a fair and accurate summary of the petitioners' second letter of objection on this matter, and he was correct to conclude that the thrust of the petitioners' objections in the second letter concerned a risk of flooding resulting from water being directed away from Barnview towards Cranmore Drive and the Tower Brae Burn. There was nothing to suggest that the petitioners were concerned with the effect that groundwater might have on the petitioners' property.

[30] On the issue of the potential for an aquifer, the materiality of such a potential and the respondents' consideration of this matter, senior and junior counsel for the interested party adopted the submissions for the respondents. The treatment of this issue by Fairhurst in their letter dated 3 July 2009 should not be construed as a statute might be; it is not even a report to Committee, but a response to a query about a site specific problem. Fairhurst had carried out sufficient investigations to enable them to form a professional opinion. They did not assert that the presence of an aquifer was impossible, but they discounted it as a problem which might cause or contribute to groundwater flooding.

[31] Fairhurst were not concerned in carrying out a hydro-geological investigation of the site as an end in itself, but for the purpose of preparing specific designs for groundwater and surface water drainage. They were satisfied that their drainage design proposals would result in an improvement on the pre-existing state of affairs; they advised the respondents' planning officer that there was no evidence of an aquifer present, both from onsite inspections or within the site investigation studies, but in any event any aquifer would be at such a depth that the development works would not affect it. The planning officer passed on this advice verbatim to the respondents' Committee. It was not suggested by anybody that the respondents were not acting reasonably in relying on the expert advice provided by Fairhurst. Moreover, the respondents were entitled to take into account as a material consideration the response by SEPA, a body which had statutory powers and duties in this regard, and which expressed support for Fairhurst's proposals and had no concerns arising from them.

[32] On the question of whether the respondents had reached their decision on an incorrect basis of fact, senior counsel for the interested party drew our attention to the observation of Lord Slynn in R v Criminal Injuries Compensation Board, ex p A [1999] 2 AC 330, referred to by the court in E v Home Secretary at paragraph 47, that "there is no onus on the board to go out to look for evidence, nor does the board have a duty to adjourn the case for further inquiries if the applicant does not ask for one". The court in E v Home Secretary went on (at paragraph 63) to analyse unfairness arising from a mistake as to, or ignorance of, a relevant fact. Senior counsel drew attention to the second of the five factors identified there, namely that the fact was "established". This factor was not present here - there was nothing to "establish" that an aquifer was present on this site, nor that if there was an aquifer on the site this would affect the risk of groundwater flooding and Fairhurst's proposed designs. There was no objective and uncontentious evidence that the respondents were wrong, or that there was any factual information which they should have taken into account when reaching their decision which they did not take into account.

Discussion
[33] We are not persuaded that the Lord Ordinary erred in his treatment of this issue at paragraphs [37] to [46] of his Opinion. He was entitled to reach the conclusion which he expressed at paragraph [46] that he was not persuaded that the respondents failed to give adequate consideration to any of the objections taken by the petitioners. We have reached the same conclusion.

[34] The possibility that there may be an aquifer in which flow is dominantly in fissures and other discontinuities in the bedrock under the site, or the vicinity of the site, is raised only by the Hydro-Geological Map of Scotland dated 1988. As the explanatory notes to that map make clear, it indicates aquifer potential in necessarily generalised terms. It shows that several of the major conurbations in Scotland have been built on similarly categorised land - including Dundee, Perth, Inverness, parts of Edinburgh and parts of Greater Glasgow. There is nothing in this map, nor in any of the investigations carried out by Fairhurst (which included onsite inspections, site investigation studies and the digging of bore holes on site) to indicate that an aquifer was present under this site, nor that the mere possibility of the presence of an aquifer should be elevated to the status of a material consideration. In any event, the detailed designs provided by Fairhurst for the interested party and submitted to the respondents were intended to deal with the risk of groundwater flooding from whatever source. As Fairhurst observed in their letter dated 3 July 2009, the development will result in only the shallow sub-soils being affected; if there is an aquifer under the site, it would be at such a depth that the development works would not affect it.

[35] It appears to us that Fairhurst were aware that there were high and uneven levels of groundwater on the site and that they applied their professional judgement to this issue, which it has been openly and logically discussed in the various reports and assessments which they provided. These reports were in turn fairly and accurately summarised by the respondents' planning officer in his reports to Committee. The issue of groundwater was before the respondents when they took their decision to grant planning permission, and we do not consider that it can be argued that they failed to take account of this consideration. The weight to be attached to a relevant consideration is a matter for the decision-maker, provided that he does not act unreasonably. In the present case, issues of groundwater flooding were considered and addressed by those professionals who were advising the developers, and were fairly put before the respondents. There is nothing to suggest that the respondents did not give adequate consideration to this issue. The body with statutory responsibility for the issue, namely SEPA, expressed no criticisms or concerns about the proposals, and stated that they were satisfied with the planning officer's suggested conditions (which were, in this respect, attached to the grant of planning permission).

[36] The argument that the respondents reached their decision on the basis of a mistake of fact, such as was discussed in E v Home Secretary, was not advanced before the Lord Ordinary, nor did it feature in the grounds of appeal for the petitioners and reclaimers. We do not consider that the argument is well-founded in the circumstances of this case. As discussed above, issues of groundwater were the subject of consideration in several reports and assessments submitted to the respondents on behalf of the interested party. The expert advice available to the respondents was to the effect that there was no evidence of an aquifer and that in any event an aquifer would be at a depth that the development works would not affect. The design set out in the proposals was stated to be such that it would cope with groundwater from whatever source, and that it would result in an improvement in the pre-existing situation. There was no contradictory expert advice. In these circumstances, to adapt the terminology of Lord Slynn in R v Criminal Injuries Compensation Board, we do not consider that there was any onus on the respondents to go out to look for evidence, nor did they have a duty to adjourn the case for further inquiries if nobody asked them to do so. Moreover, as senior counsel for the interested party observed, the second of the five factors discussed by the Court of Appeal in E v Home Secretary is absent in this case. The fact that there is an aquifer on this site has not been "established" in the sense that it is uncontentious and objectively verifiable. Accordingly, while it may be that a mistake of fact giving rise to unfairness is now properly to be regarded as a separate head of challenge in an appeal on a point of law, we do not consider that a challenge to the decision presently under consideration can succeed on this ground.

[37] On the first issue argued before us, we reach the conclusion that the petitioners and reclaimers must fail.

Issue (2):

The change of planning policy requiring a precautionary approach to be taken to flood risk
[38] The Lord Ordinary set out the background to this aspect of the dispute at paragraphs [22] to [31] of his opinion, as follows:

[22] On 23 September 2009 when the Council resolved, in principle, to grant the planning application, the relevant National Planning Policy on assessing flood risk was contained in Scottish Planning Policy 7 entitled: "Planning and Flooding" ("SPP 7"). This had been published by the Scottish Executive Development Department in February 2004. It is clear that the Council applied this policy in their handling of and approach to the application. The summary at the beginning of the policy document expressly stated that the Scottish Executive expected developers and planning authorities to err on the side of caution in decision making whenever flooding was an issue. In the same section the policy document explained that flood risk would be a material consideration in a range of cases. The policy stated that new development should not take place if it would be at significant risk of flooding from any source or would materially increase the probability of flooding elsewhere.

[23] The general principles underlying the policy were set out in paragraph 15 of the document. These principles included the following:

· Developers and planning authorities were required to give consideration to the possibility of flooding from all sources.

· New development was to be free from significant flood risk from any source.

· In areas characterised as "medium to high" flood risk for watercourse and coastal flooding new development was to be focused on built up areas and all development had to be safeguarded from the risk of flooding.

· New development was not to increase materially the probability of flooding elsewhere.

· Flooding from sources other than watercourses and on the coast had to be addressed where new development was proposed, if necessary through a drainage assessment. Any drainage measures proposed were required to have a neutral or better effect on the risk of flooding both on and off the site.

[24] The policy applying those principles was set out in considerable detail between paragraphs 16 and 37 of SPP 7. Some important features of the policy may be noted. In paragraph 21 it was recognised that if natural drainage patterns were disturbed by development, flooding might also be caused. Drainage was therefore stated to be a material planning consideration. Drainage measures proposed as part of a planning application were to have a neutral or better effect on the risk of flooding both on and off the site. It was noted that planning authorities had a duty to consult SEPA on appropriate planning applications. Paragraph 22 observed that the primary role of sustainable drainage systems (SUDS) was to manage the flow of rain water run-off from a site by treating it on site, thereby reducing the loading on conventional piped drainage systems. It was noted that some sustainable drainage systems, such as detention ponds, could slow the rate of run-off by temporarily storing water.

[25] In paragraphs 33 to 37 the planning approach to assessing the risk of flooding was set out in detail. In paragraph 33 the policy document observed that even in areas generally free from flooding, local conditions and exceptional rainfall could lead to flooding. It was therefore not possible to set planning policy and determine applications solely according to the calculated probability of river or coastal flooding. Nevertheless, in order to provide a basis for decision making, a characterisation of flood risk into "little or none", "low to medium" and "medium to high" was set out in a risk framework even though it was recognised that this simplified the situation. For each level of risk an appropriate planning response was outlined.

[26] Paragraph 37 observed that the Risk Framework was based on the annual probability of flooding. In applying the Risk Framework developers and planning authorities were required also to take into account a number of considerations depending on the particular circumstances. These included: the characteristics of the site; the use and design of the proposed development; the size of the area likely to flood; and the cumulative effects of development. It was then explained that the calculated probability of a flood occurring should be regarded as a best estimate and not a precise forecast. Developers and planning authorities were therefore required to err on the side of caution in taking decisions when flood risk was an issue.

[27] In the concluding section of SPP 7, paragraph 53 stated the following:

"The Scottish Executive expects developers and planning authorities to deal very seriously with flooding, to take an informed approach to decision making and err on the side of caution where flood risk is an issue. When owners accept their primary responsibility for safeguarding and ensuring their land and property against flooding they should be able to do so in the expectation that the planning authority and the developer have properly had regard to the probability of flooding and the associated risk."

[28] In April 2009 the Scottish Government issued a consultative draft document on Scottish planning policy. As part of its commitment to proportionate and practical planning policies, the Government had decided to rationalise the series of national planning policy documents (the SPP and NPPG series) into a single statement of national planning policy. The first part of the consolidated Scottish Planning Policy (SPP) had been published in October 2008 and covered the core principles, aspirations and expectations for the planning system. The consultation embarked on in April 2009 covered inter alia the subject policies which were expressed through seventeen separate SPPs and NPPGs. It was made clear in the introduction to the consultative draft that the consolidation of the subject policies into the single SPP was not a review of established policy. The aim was to rationalise existing policy and to express it in more concise terms, providing clarity and greater certainty of intended outcomes. It was noted that the changes in wording did not, in most cases, represent a change in policy. One of the SPPs to be superseded by the SPP, when published in its final form, was to be SPP 7.

[29] The section in the consultative draft dealing with flooding and drainage was contained between paragraphs 151 and 162. These paragraphs make it entirely clear that no substantive change to national planning policy on the assessment of flood risk was intended. Existing policy was set out in more concise terms, but the content and approach remained unaltered. In particular, in paragraph 153 it was stated that developers and planning authorities should err on the side of caution in taking decisions when flood risk was an issue. This was because even in areas generally free from flooding, local conditions and exceptional rainfall could lead to flooding. It was therefore not possible to set planning policy and determine applications solely according to the calculated risk of flooding. It will be seen that the language used in this part of the consultative draft echoed the approach advocated in SPP 7 in regard to erring on the side of caution and put forward the same justification for that approach. Paragraph 155 of the consultative draft set out, in terms which were not materially different from those to be found in SPP 7, the Risk Framework which divided flood risk into three categories and outlined an appropriate planning response.

[30] In February 2010 (shortly before the formal grant of planning permission in the present case, but some months after the resolution to grant consent in principle) the Scottish Government published the final version of the new Scottish Planning Policy ("the SPP"). Although this now reflected some minor adjustments to national planning policy because of the enactment of the Flood Risk Management (Scotland) Act 2009, the final document followed very closely the terms of the consultative draft. There was, however, one change in the language used. In paragraph 202 it was now stated that developers and planning authorities should take a precautionary approach in taking decisions when flood risk was an issue. The earlier reference to "erring on the side of caution" in the corresponding section of the consultative draft was replaced by reference to the taking of a "precautionary approach". The rest of the passage was unchanged, however. In particular, the justification for advocating the recommended approach was the same as before; the policy continued to say that local conditions and exceptional rainfall could lead to flooding and it was, therefore, not possible to set planning policy and determine applications solely according to the calculated probability of flooding.

[31] The reason for this alteration in the language used is explained in a document published by the Scottish Government in July 2010 entitled "Scottish Planning Policy - Post-Adoption Strategic Environmental Assessment (SEA) Statement". This (like the other documents explaining the evolution of national planning policy) was lodged at a late stage during the First Hearing. In paragraph 2.37 the SEA noted that some consultees (on the draft SPP) had suggested that strengthening of the policy was required to emphasise a precautionary approach. In paragraph 2.38 it was noted that the finalised SPP had been "slightly amended" to reflect consultee views, including by noting the need for a precautionary approach to flood management. There is no suggestion in the assessment (or indeed in any other document that was put before me) that a significant change in the substance of national planning policy was intended by this slight adjustment in language, which took place in the context of a consolidation exercise."

[39] At paragraph [34] of his Opinion the Lord Ordinary set out the petitioners' ground of challenge on this point, namely that when the respondents came to consider whether formally to grant planning permission after the section 75 Agreement had been entered into, they were bound to have regard to the SPP because the reference to a precautionary approach in paragraph 202 amounted to a new material consideration. He considered the authorities to which he was referred on the meaning of a material consideration in this context (Kides, supra; John G Russell (Transport) Ltd v Strathkelvin District Council 1992 SLT 1001, and section 37(2) of the Town & Country Planning (Scotland) Act 1997), and then noted the discussion which took place before him as to the origins and meaning of the precautionary principle, under reference to the application of a precautionary approach in the context of environmental law. He then set out his reasoning and conclusion on this issue in paragraph [36] of his Opinion in the following terms:

"[36] Whatever part the precautionary principle or approach may have to play in European environmental law, the real question in the present case, as it seems to me, is whether the SPP, by its reference to the taking of a precautionary approach to flood risk in paragraph 202, introduced (as the petitioners say it did) a new material consideration. In my opinion, it is clear that the intention and effect of the SPP was not to make any substantive change in national planning policy in regard to the approach to assessing flood risk. Read in context, the change in language from "erring on the side of caution" to "taking a precautionary approach" was clearly intended to be one of expression as opposed to one of substance. As is explained in the SEA, it was evidently decided to make a slight alteration in the language used in this section of the policy in order to reflect the responses of certain consultees; their view apparently being that the wording of the policy should be strengthened "to emphasise a precautionary approach". In my opinion, this change was no more than textual or cosmetic; the intention was to express somewhat more emphatically the precautionary nature of the existing policy and not to introduce a new and different policy approach. It is notable that the surrounding text was left unaltered. It is significant also that the Scottish Government took no steps to consult on the change; had the intention been to introduce a substantive alteration to planning policy in this sensitive area it is inevitable that there would have been further consultation on the matter. Beyond the mere change in the words used, nothing was done to indicate that an important alteration in planning policy was being effected. It seems to me that SPP 7 already advocated a precautionary approach by its use of the words "err on the side of caution" and that the purpose of the amendment was simply to express this existing approach somewhat more pointedly. Accordingly, the change in the words did not reflect any material change in national planning policy. In the circumstances, I am not persuaded that there was a new material consideration to which the respondents required to have regard before they formally granted planning permission on 5 March 2010. The petitioners' first ground of challenge accordingly falls to be rejected."

[40] Counsel for the petitioners and reclaimers argued that the Lord Ordinary erred in his conclusion that the change was no more than textual or cosmetic and did not reflect any material change in national planning policy. They were unaware of any statutory definition of "a precautionary approach" in European or domestic legislation, but it clearly meant more than "erring on the side of caution". There was a clear change of emphasis in recent government guidance and legislation, requiring steps to be taken before any decision is made rather than simply erring on the side of caution. For example, Regulation 24 of the Town & Country Planning (Development Management Procedure) (Scotland) Regulations 2008 provided that a planning authority may require from the applicant further particulars, documents, materials or evidence which they consider that they require to enable them to deal with the application. By section 42 of the Flood Risk Management (Scotland) Act 2009 (which is not yet in force) this provision is amended from a power to a duty by the insertion of the words:

"must, where the application relates to a development that is likely to result in a material increase in the number of buildings at risk of being damaged by flooding, require from the applicant an assessment of flood risk in respect of the development."

[41] This was an indication, it was submitted, of an important shift in policy from general encouragement to more rigorous, mandatory requirement. Although, as the Lord Ordinary observed, it was stated in the consultative draft of the SPP that it was not a review of established policy and that changes in wording did not, in most cases, represent a change in policy, the consultation process did result in national planning policy changes to reflect two significant pieces of legislation, as was apparent from the report on Scottish Planning Policy - Proposed Policy Changes Consultation dated September 2009. This resulted in the introduction of the concept of "a precautionary approach" in taking decisions when flood risk is an issue, introduced in paragraph 202 of the SPP. That this was intended to represent an amendment to planning policy was clear from the terms of paragraphs 2.37 and 2.38 of the Post-Adoption Strategic Environmental Assessment (SEA) Statement published in July 2010 and referred to by the Lord Ordinary at paragraph [31] of his Opinion.

[42] Counsel sought support for the proposition that a precautionary approach was an important new policy from article 191 of the Treaty on the Functioning of the European Union (formerly article 174 of the EC Treaty). He referred to Jans & Vedder on European Environmental Law (3^rd Edition) at pages 37/38; R (on the Application of the Environment Agency) v Tonbridge Malling BC [2005] EWHC 3261 (Admin); [2006] 2 P. & C.R. 28; R (on the Application of Hulme) v Secretary of State for Communities and Local Government [2010] EWHC 2386 (Admin); Kides (supra); and Tesco Stores Ltd v Dundee City Council [2012] UKSC 13, 2012 SLT 739 (particularly at paragraphs [18] and [19]). Counsel submitted that what was in issue in the present case was not the precise meaning of a precautionary approach, but whether the insertion of these words effected a material change in approach. On the basis of Tesco v Dundee City Council this was a matter of law to be decided by the court. It was submitted that this did amount to a material change which might have made a difference to the respondents' consideration of the application (albeit that it may not have been determinative). It should have caused the respondents to think about requiring a flood risk assessment in respect of flooding of the Tower Brae Burn, and groundwater flooding. Paragraph 206 of SPP published in February 2010, went beyond SPP 7. This was a material consideration which the planning officer was bound to draw to the attention of the respondents before they reached their decision to grant planning permission on 5 March 2010.

[43] For the respondents it was submitted that the Lord Ordinary was correct to conclude that there was no material change in flood risk policy, and accordingly no new material consideration to which the respondents required to have regard before they formally granted planning permission on 5 March 2010. The correct interpretation of planning policy is an issue of law, reading the words used objectively in their proper context (Tesco Stores v Dundee City Council at paragraphs 18/21 and 35). The Post-Adoption Strategic Environmental Assessment (SEA) Statement which was published in July 2010 (several months after the grant of planning permission by the respondents) cannot properly be used as an aid to interpretation of SPP. In any event, it does not support the petitioners' construction of SPP. Moreover, the respondents did in any event adopt a precautionary approach, and complied with the policy advice in SPP. They were in fact taking a precautionary approach, and the circumstances were analogous to those in Hulme. Integral to the design of the approved proposals was a lowering of the point at which groundwater can spill away from the detention area, and a significant increase in the total volume of water that can be attenuated. The development has been designed in such a way as to avoid the areas susceptible to ponding of water.

[44] Counsel submitted that the Tonbridge Malling BC case was of little assistance to the court in the present case - the emphasis on avoidance in that case arose from the sequential approach in the English provisions, but a different approach is taken in the SPP, in which it is acknowledged (at paragraph 202) that "all land is to some degree susceptible to flooding". It was recognised by the authors of Jans & Vedder's European Environmental Law (at page 38) that

"According to the Commission guidelines the precautionary principle is all about 'risk management', which does not mean that all risks must be reduced to zero. Judging what is an acceptable level of risk for society is a political responsibility. Where action is deemed necessary, measures based on the precautionary principle should be proportional to the chosen level of protection ..."

[45] In any event, counsel for the respondents submitted that there was no need for the planning officer to refer this matter back to the respondents' Committee after publication of SPP. In this regard counsel referred to Kides (supra) at paragraphs 121-126. It was submitted that this passage in the judgment of Jonathan Parker LJ (with whom the rest of the Court of Appeal agreed) demonstrated that there were two components to the test as to whether an issue requires to be referred back to the decision-maker. First, it is necessary to determine whether there has been a material change of policy - that is to say, is it

"a factor which, when placed in the decision-maker's scales, would tip the balance to some extent, one way or the other. In other words, it must be a factor which has some weight in the decision-making process, although plainly it may not be determinative."

However, at paragraph 126 the court gave guidance in practical terms where, since the passing of a resolution to grant planning consent subject to conclusion of an agreement, some new factor has arisen of which an officer is aware and which might rationally be regarded as a "material consideration". In the present case, the respondents' planning officer was aware of the issuing of SPP; he read it and noted the change in the text, and reached the view that the precautionary approach had been fulfilled by the respondents in this case. The case of Dry (supra) is relevant in this context. The Court of Appeal considered the guidance in Kides (at [126]); at paragraph 16 of his Opinion Carnwath LJ (with whom Maurice-Kay and Patten LJJ agreed) observed as follows:

"Without seeking to detract from the authority of the guidance in Kides, I would emphasise that it is only guidance as to what is advisable, 'erring on the side of caution'. Furthermore, in that case there had been a gap of five years between the resolution and the issue of the permission. The guidance must be applied with commonsense, and with regard to the facts of the particular case."

In the present case, SPP 7 had already advocated what amounted to a precautionary approach, and the developers and the respondents had taken a precautionary approach. There was no need to refer this matter back to the Committee.

[46] Senior counsel for the respondents summarised the submissions on their behalf as follows:-

(i) The Lord Ordinary was correct in holding that there was no material change of planning policy between SPP7 and SPP. The fact that there is a difference of wording does not mean that there is a difference of meaning. A precautionary approach is in substance no different from erring on the side of caution.

(ii) If there is any difference, its effect cannot be measured, and it is not material.

(iii) Before the court can quash a decision, it must be satisfied not only that the decision-maker failed to take into account a matter, but also that there is a real possibility that the decision-maker would reach a different conclusion if he did take that consideration into account - see the second and third of Glidewell LJ's principles in Bolton MBC v Secretary of State for the Environment at page 352. That is why it is necessary to know what was changed in national planning policy, in order to decide whether it would have given rise to such a real possibility. Even if there was an intention to change the emphasis, or adjust the balance, the petitioners' submissions failed the test in Bolton MBC.

[47] Counsel for the interested party adopted the submissions for the respondents on this point. They submitted that it would be strange if a significant change in national planning policy was effected by the SPP standing the introductory words to the document, and that the significance of such a change would not become apparent until the publication of a Post-Adoption Statement some months after publication of the SPP. The change in the wording of the SPP as compared to SPP 7 was so subtle that, if it was intended to be a significant change, one would expect this to have been clearly stated. It failed the second and third of Glidewell LJ's tests.

[48] It had been submitted by senior counsel for the petitioners that the precautionary approach emphasises the need for caution before the decision was made; however, in this case the respondents did take account of all the information regarding the risk of groundwater flooding and the proposals to deal with this before they reached their decision, and they did so erring on the side of caution.

[49] Senior counsel for the interested party observed that the policy in SPP is that developers and planning authorities should "take a precautionary approach". There is a "precautionary principle" in European environmental law, but neither is a term of art, and this is emphasised by the fact that SPP refers to "a" rather than "the" precautionary approach. It is not clear how this differs from erring on the side of caution, and if it does, in what respect. The change of wording between SPP 7 and SPP was no more than a change of emphasis. The statement at paragraph 2.38 of the July 2010 Post-Adoption Statement that "the finalised SPP has been slighted amended to reflect consultee views, including by noting the need for a precautionary approach to flood management" is not consistent with this amounting to a material consideration.

Discussion
[50] In determining this issue, it is necessary to compare the terms of SPP 7: Planning and Flooding (published in February 2004) with the terms of the SPP published in February 2010. The opening paragraph of SPP 7 was summarised by the Lord Ordinary at paragraph [22] of his Opinion, quoted above. The Scottish Executive expected developers and planning authorities to err on the side of caution in decision-making whenever flooding is an issue. Paragraph 202 of SPP, which is headed "Flood Risk", contains the statement that "Developers and planning authorities should take a precautionary approach in taking decisions when flood risk is an issue."

[51] For the reasons which he gave in paragraph [36] of his Opinion, the Lord Ordinary reached the view that this change was no more than textual or cosmetic. There were no steps to consult on the change, and beyond the mere change in the words used, nothing was done to indicate that an important alteration in planning policy was being effected. He concluded that the purpose of the amendment was simply to express the existing approach somewhat more pointedly. We have some sympathy with this approach; if it was intended to effect a significant change in planning policy, one might have expected the Scottish Government to have made this abundantly clear, particularly when the consultative draft SPP which was issued in April 2009 contained in its introductory paragraphs the following statement:

"The consolidation of the subject policies into the single SPP is not a review of established policy. Existing policy is being rationalised and expressed in more concise terms, providing clarity and greater certainty of intended outcomes. The new style of SPP requires a different approach to expressing and explaining national planning policy, but the changes in wording do not, in most cases, represent a change in policy."

[52] Moreover, one can appreciate the observations by counsel for the respondents and the interested party that the change from erring on the side of caution to taking a precautionary approach is subtle. The exact consequence of this change of wording is not clear. The term "a precautionary approach" is not a term of art. It is not clear whether it is precisely equivalent to "the precautionary principle", which is used in other contexts and is similarly not a term of art. What is it that a planning authority would do differently in taking a decision when flood risk is an issue, by adopting a precautionary approach rather than erring on the side of caution?

[53] However, with some hesitation we have reached the conclusion that it would not be right, as the Lord Ordinary does at one point, to categorise the change in the wording as simply textual or cosmetic. We consider that there was some change in national planning policy with regard to flood risk effected by SPP. There are several sources which tend to suggest that it was the intention of the Scottish Government to strengthen planning policy on the issue of assessment of flood risk and flood protection/alleviation measures. The amendment of regulation 24 of the Town & Country Planning (Development Management Procedure) (Scotland) Regulations 2008 by section 42 of the Flood Risk Management (Scotland) Act 2009 is one of these. Although section 42 of the 2009 Act is not yet in force, it does indicate a policy on the part of the Scottish Parliament to require rather more stringent scrutiny of development proposals which are likely to result in a material increase in the number of buildings at risk of being damaged by flooding. A power is changed to a duty. Although the statutory provision is not in force, it is suggestive of a shift in national planning policy (although the 2009 Act does not itself refer to a precautionary approach.)

[54] That some change in national planning policy on this issue was intended was reinforced by the document entitled "Scottish Planning Policy - Proposed Policy Changes Consultation" issued in September 2009. Paragraph 3 of that document is in the following terms:

"Since the publication of the draft consolidated SPP two significant pieces of legislation had been passed by the Scottish Parliament which have implications for national planning policy. These are the Flood Risk Management (Scotland) Act 2009 and the Climate Change (Scotland) Act 2009. Changes to national planning policy to reflect new legislation need to be incorporated into the final SPP and an assessment of the effects of the proposed changes is required as part of the SEA."

[55] That there was an intention to make some change to national planning policy on this issue receives further support from the Post-Adoption Strategic Environmental Assessment (SEA) Statement dated July 2010. Although it is correct to observe that this was not published until some months after the SPP, and some months after the respondents decided to grant planning permission on 5 March 2010, we consider that it is properly available to us as a document which sheds light on whether there was an intention to effect a change in national planning policy. The statements in paragraph 2.37 and 2.38 of this document support the view that it was intended to strengthen planning policy on this issue. Paragraph 2.37 includes the statement that

"A further view was that the balance within the policy was too heavily in support of flood risk management as opposed to avoidance, and this linked with suggestions from other consultees that strengthening of the policy was required to emphasise a precautionary approach."

Paragraph 2.38 stated that: "The finalised SPP has been slightly amended to reflect consultee views, including by noting the need for a precautionary approach to flood management... ".

[56] Considering all the information before us, we have reached the view that there was indeed some change in national planning policy on this issue which was effected by SPP in February 2010. However, we are of the view that the effect of the "slight amendment" in the finalised SPP was relatively minor - in colloquial terms, perhaps "fine tuning".

[57] We were told that the planning officer considered the terms of the SPP and reached the view that both the interested party and the respondents had in fact taken a precautionary approach in relation to this proposed development. We do not consider that it can be said that he erred in reaching this conclusion. We agree with the observations of the Court of Appeal in Dry (supra) (at paragraph 16) that the guidance given in Kides must be applied with commonsense, and with regard to the facts of the particular case. Adopting the language of Glidewell LJ in the second and third of the principles which he stated in Bolton MBC, we cannot say that there is any real possibility that the respondents would have reached a different conclusion if the reference to a precautionary approach in the SPP had been drawn to their attention before the planning consent was finally issued on 5 March 2010.

[58] For these reasons, we are not prepared to quash the decision of the respondents on this ground.

Conclusions

[59] It follows from the above that neither of the grounds on which the petitioners sought review of the interlocutor of the Lord Ordinary dated 19 August 2011 succeed, and this reclaiming motion must be refused. In the result, the issues raised on behalf of the respondents and the interested party regarding mora, taciturnity and acquiescence and the court's ultimate discretion to refuse the remedy sought do not arise. We were favoured with interesting and well-argued submissions on both sides of each of these issues, but as they are not necessary for the determination of this reclaiming motion we do not consider we need to express a view on them. For the reasons given above, we shall adhere to the interlocutor of the Lord Ordinary dated 19 August 2011 to the extent of sustaining the seventh and eighth pleas-in-law for the respondents, sustaining the fifth and sixth pleas-in-law for the interested party, and repelling the plea-in-law for the petitioners. We shall refuse this reclaiming motion.