Rescue is offering ideas and comment in the following paper about the impact on archaeology of the changes to pre-commencement planning conditions which come into force in October. We welcome any constructive comments on this.
Pre-Commencement Conditions & obtaining applicant consent: Archaeology
Introduction:
The process of assessing, identifying and removing archaeological remains from a site threatened by development has been an integral part of the planning process since the drafting and adoption of PPG16 in 1990. That these archaeological tasks must largely take place before development commences is clearly an unavoidable fact given the nature of the majority of the archaeological resource and, up until recently, this process has been governed by the imposition on planning permissions of an archaeological condition that begins “No development shall take place until…”. This is all about to change under the Town & Country Planning Act (Pre-commencement Conditions) Regulations 2018 which come into force on 1 October. Unless new and/or alternative ways of working are explored, the process of archaeological investigation within the context of the planning process may well be under serious threat.
Recent practice has focussed on the assessment and evaluation phases of the archaeological process being carried out prior to determination of an application, although mitigation work is still largely regulated and managed via the imposition of schemes agreed as part of post-determination but pre-commencement conditions.
The Government’s forthcoming changes to the planning process will create a procedure which will require asking applicants to agree to accept any pre-commencement conditions that the Local Authority might consider necessary, rather than simply imposing conditions as is the case currently. In future, where it is not agreed by the applicant the condition cannot be added. The Government anticipates this scenario will be uncommon – although many planning officers and archaeologists hold a more cynical view that the underlying principle behind these measures is to make the use of pre-commencement conditions much harder, or even to dissuade local authorities from using them altogether.
The general consensus amongst the wider local authority planning community is that the new measures are confusing, badly worded, will be difficult to conduct and enforce, will result in additional bureaucracy and will almost certainly introduce unnecessarily adversarial discourse into the planning process. The changes have similarly not been welcomed by the archaeological profession and there have been attempts to try to convince the Government to exempt archaeological conditions from this requirement given their inherent and virtually default pre-commencement nature. There are provisions in the legislation to allow for the Secretary of State to do this: however at present no exemptions are in place and attempts to persuade the government of a need to create a special status for archaeological responses (amongst others) to planning applications have thus far failed.
Should agreement with a developer to accept archaeological conditions not be achieved, it will leave a very limited set of options available to the archaeologist and planner – and this threatens to undermine the archaeological planning process and could potentially lead to a loss of a significant amount of archaeological information if conditions are omitted from permissions as a result. Provision for accommodating the controlled and orderly removal of archaeological remains from a site within the planning process is still retained within the newly-published National Planning Policy Framework, but the process of doing so may become a contentious issue in the very near future when the new measures come into full effect in October. This paper is not intended to be one which offers any definitive solutions to what is likely to be a difficult problem for archaeologists and planners to resolve. However it may be of value to explore a few of the approaches that have been suggested by a number of respondents to address the archaeological issues, to enable local authorities to assess the various concerns and make decisions over what approach to adopt on a case-by-case basis. The final section of this paper deals with the Government’s own suggested approaches and makes some recommendations about the viability of adopting these with reference to the needs of the archaeological resource.
Addressing the Archaeological Process – Suggested Approaches:
- Additional front-loading of the decision-making process:
Regardless of the site in question, the archaeological process involves a fairly regular series of defined phases of work:
Assessment
Evaluation
Mitigation
Post-fieldwork Reporting and Publication
Archiving
Clearly there are differences in the specific techniques and their application that might be employed on a site, as no two archaeological sites are the same. There are also subtle nuances in the appropriate timing of certain works but broadly most projects will proceed along these lines. Current practice – as set out in the NPPF and the Local Plans – is to require the assessment of archaeological sensitivity to be carried out and the results to be submitted with a planning application either through a desk-based assessment document or through an EIA. An application can be refused validation if an archaeological or heritage assessment is required and is not submitted.
As part of the consideration of the application, it might be that the assessment has identified concerns or ambiguities that require investigation, and that the results of an evaluation (trial trenching, geophysics etc.) can be requested. In some cases evaluation results are necessary in order to inform the decision, but there is some flexibility in the process and there are some cases where evaluation can be carried out post-determination in response to the terms of a pre-commencement condition, or where assessment can lead directly into the mitigation phase (watching briefs, monitored site stripping). The mitigation and subsequent work are most commonly managed through the use of pre-commencement conditions, to ensure that any remains encountered are recorded prior to their destruction by the development.
The use of pre-commencement conditions could be reduced somewhat by front-loading the application process to include the results of field evaluation work as standard, by adding archaeological evaluation to the list of validation requirements. Unfortunately this would reduce flexibility in how the archaeological planning process is managed, and might lead to an increase in applications being refused validation. It would mean that submissions would be rigidly required to produce more detailed information at an earlier stage, and where it was absent, validation could be withheld. It might lead to an increase in unnecessary and perhaps negative evaluations as investigation would by definition need to be enforced on sites where in the past a more flexible approach would have assessed on a case-by-case basis and rejected the need to investigate certain sites. Such an approach would be easier to manage locally and would also increase the justification for any subsequent request of agreement to the imposition of a pre-commencement condition to manage mitigation works, as the information demonstrating its necessity would be more apparent to all parties earlier in the process. However this approach would be difficult to adopt as a universal solution, as the requirement for all developers to submit the results of an evaluation regardless of the archaeological need, would appear unreasonable.
2, Application Validation and requesting that the applicant accept conditions:
The planning validation process outlines the information that an applicant is required to provide. Where a site meets certain criteria – for example is within or adjacent to a pre-defined area of archaeological significance or potential, or over a certain area in size – the applicant is required to supply archaeological assessment information. It has been suggested that as part of the submission and checking process of validation it would be possible to ask the applicant if they would accept the use of a pre-commencement condition should permission be considered. This would fulfil the Government’s objective and also allow for a considerably longer period of discussion with the applicant. The downside of this approach is that it’s at a very preliminary stage and the question is asked before the ramifications of the decision might be apparent. Applicants might well be reluctant to accept conditions so early on and before their financial risks have been identified.
The form of questions and explanation might also be fairly cumbersome. A suggested validation form query along these lines is set out below:
“Where a site is either within or adjacent to an area of archaeological sensitivity or potential, submission of archaeological information in the form of an acceptable desk-based assessment is required.
Is the site within or adjacent to an area of archaeological concern? Yes / No
Where you have answered “Yes”, have you included the required archaeological information? Yes / No
Recent changes to planning legislation require that should planning permission be granted, the use of any pre-commencement conditions must be agreed with applicants beforehand. Should archaeological material be present on the application site it might be necessary to request your agreement to a pre-commencement condition in order to secure its recording and facilitate development. Without prejudice to the decision-making process, would you be willing at this stage to accept such a condition if archaeological remains are present on the development site that are threatened by the proposals and require removal prior to development? Yes / No
Note: Answering Yes does not guarantee that such a condition will be necessary or that planning permission will be granted, but will assist with issuing a positive decision in the event such a determination is made. Answering No similarly does not mean that such agreement might not be sought later in the process should archaeological remains be identified. However answering No might introduce a delay in the process later.”
It is also worth remembering that the Government requires that in order to agree to the imposition of a condition, an applicant needs to be made aware of the precise wording that is proposed. Despite being cumbersome, the suggested wording outlined above does not do this. This approach is possible, but seems likely to confuse the process and may not be compliant with the terms of the new legislation. There would also need to be an opportunity for the applicant to change their mind later in the process, which would appear to render this possible solution procedurally redundant. Nevertheless, it may be that there are opportunities within the application validation process for the archaeological profession to achieve higher levels of information gathering in requiring the submission of more than just desk-based assessment (see above), and in a changing legislative landscape with few guiding principles, these might usefully be explored.
- Altering the wording of archaeological conditions:
The standard pre-commencement archaeological condition used nationally is generally the model (or variant of) the wording given in Planning Circular 11/95. The Circular itself went out of use in 2014, but Appendix A (Model Conditions) has been retained. The archaeological model condition recommended as standard in Circular 11/95 is:
“No development shall take place within the area indicated until the applicant, or their agents or successors in title, has secured the implementation of a programme of archaeological work in accordance with a Written Scheme of Investigation which has been submitted by the applicant and approved by the Planning Authority.”
In order to circumvent the requirement for obtaining applicants’ consent to pre-commencement conditions, this wording might be altered to mean the condition being used is not pre-commencement in nature, but is simply pre-damage to any archaeological deposits, for example:
“No works below current ground levels shall take place within the area indicated, until the applicant, or their agents or successors in title, has secured the implementation of a programme of archaeological work in accordance with a Written Scheme of Investigation which has been submitted by the applicant and approved by the Planning Authority.”
Or even more simply:
“The applicant, or their agents or successors in title, shall implement a programme of archaeological work within the area indicated, in accordance with a Written Scheme of Investigation which has been submitted by the applicant and approved by the Planning Authority.”
This would allow development work on site to commence and would allow for works such as demolition or site clearance to take place, but would prohibit potentially damaging below-ground excavations until such time as the applicant has submitted and agreed a mitigation scheme. Although a viable consideration for a number of situations where archaeological remains might be at risk, this solution is not ideal and wouldn’t cover all schemes of archaeological work – for example, archaeological standing building recording would still need to be carried out prior to demolition or site clearance, so would not be covered by the terms of the first suggested condition above. This suggested approach may fail one of the “six tests” of a planning condition (see below), in that both suggested conditions lack a degree of precision. Also, the current condition does not actually specify that any archaeological work should take place prior to development – just that there should be a written scheme for that work agreed and in place before development. This is an important point of semantics to bear in mind if and when considering redesigning the archaeological condition, as the principle of carefully wording conditions to ensure that only certain aspects of the development programme are excluded, is an approach already in place.
Another approach, and one which some authorities have already adopted, would be to completely revise the recommended archaeological condition and abandon the model condition of Circular 11/95 entirely. Some attempts to do this have been undertaken in recent years to address other issues, and there is currently a (not particularly satisfactory) alternative model condition suggested in the NPPF-supporting document Good Practice Advice note 2, Managing Significance in Decision-Taking in the Historic Environment (p.11), which breaks the archaeological process down into modules, to be signed off as and when they are completed so that works can be agreed and discharged at different phases of development:
“No demolition/development shall take place/commence until a written scheme of investigation (WSI) has been [submitted to and] approved by the local planning authority in writing. For land that is included within the WSI, no demolition/development shall take place other than in accordance with the agreed WSI, which shall include the statement of significance and research objectives, and
- The programme and methodology of site investigation and recording and the nomination of a competent person(s) or organisation to undertake the agreed works
- The programme for post-investigation assessment and subsequent analysis, publication & dissemination and deposition of resulting material. This part of the condition shall not be discharged until these elements have been fulfilled in accordance with the programme set out in the WSI”
This is clearly still a pre-commencement condition however, and would require revision to make it acceptable under the new system. It could potentially also cost the applicant more to discharge, as there would be a greater need for formal submissions and more paperwork to agree – a bureaucratic side effect of what is clearly poorly drafted legislation that failed to address technical concerns raised during its preparation. The approach does have the advantage, however, of allowing for phased works which can be set out in detail. Such an approach is more common on longer-term projects such as mineral extraction sites, and has been found to avoid problems later on in the process regarding post-excavation works and archiving, which have often struggled to reach completion since PPG16 first instituted planning-led archaeological work in 1990.
A “non-pre-commencement” version of this condition could be worded along the following lines:
“The applicant is required to implement a programme of archaeological work in accordance with a written scheme of investigation (WSI) which has been submitted to and approved in writing by the planning authority. The programme should include measures for:
- the protection of remains or evidence of archaeological significance during any pre-archaeological investigation phases of development,
- the timely excavation, recording, removal, assessment, reporting, publication and archiving of any archaeological material recovered from the site.
The condition shall not be discharged until these elements have been fulfilled in accordance with the programme set out in the WSI.
Reason: Archaeological evidence exists on this site which requires investigation and recovery, in line with the requirements of the NPPF.”
This would mean that “development” could commence but that the applicant would still need to set out how any archaeology would be protected until they got around to addressing its controlled removal. Although not technically worded as a “No development shall take place…” style of pre-commencement condition that prohibits starting works on site, the implication of the first bullet point is that pre-commencement is clearly the most appropriate stage for such a Written Scheme to be produced – so it still might be classed as a pre-commencement condition that requires agreement. In principle though, an applicant could actually reduce the “burden” of the condition by addressing the archaeological issues earlier, as there would be no need for onerous protection measures – which might be an incentive for applicants to timetable the archaeological works at a more convenient period. This approach, if tested, might be considered to technically breach the spirit (and the intent) of the new legislation, and a local authority considering such a course would need to bear this in mind. However, this approach could potentially address the issues regarding pre-demolition archaeological concerns involving works such as standing building recording (outlined above), since the protective measures for not damaging the resource during other works would now need to be specified as part of a condition and could be the subject of enforcement action if they were not carried out.
Having this condition classed as a pre-commencement one on appeal might be considered, but could potentially be avoided by deleting the first bullet point and wording the condition thus:
“The applicant is required to implement a programme of archaeological work in accordance with a written scheme of investigation (WSI) which has been submitted to and approved in writing by the planning authority. The programme should include measures for:
- the timely examination, excavation, recording and removal of any and all archaeologically significant material or evidence on the site
- the reporting of the results of this work to the planning authority and the Historic Environment Record
- The publication of the results as appropriate and
- The archiving of all material recovered and produced during the works at an appropriate and accredited repository
The condition shall not be discharged until these elements have been fulfilled in accordance with the programme set out in the WSI.
Reason: Archaeological evidence exists on this site which requires investigation and recovery, in line with the requirements of the NPPF.”
The planning authority should bear in mind that this approach of tweaking and itemising conditions is likely to bring alternative technical difficulties: for example, with relation to the final bullet point above, ownership of archaeological material lies with the site landowner until title is transferred. Can it be specified in a planning condition that private property is donated/appropriated in this way? This highlights just one of a number of issues that arise when attempting to reconcile the somewhat esoteric practice of archaeology into a regimented and highly regulated industry such as development, and serves as an example of what might happen if bespoke and perhaps ill-considered planning conditions begin to proliferate. If care and diligence is not undertaken this approach could be a potential minefield of legal challenges and failed and unenforceable conditions. However having looked into the possibilities, the planning and archaeological profession should conclude that there are opportunities to pursue here that might be fruitful.
- Use of Section 106 Legal Agreements:
Section 106 of the Town and Country Planning Act 1990 allows for legal arrangements between developers and local authorities to be agreed upon. These arrangements are linked to planning permissions and can also be known as Planning Obligations. The Act specifies that an enforceable agreement may be entered upon (amongst other things) “requiring specified operations or activities to be carried out in, on, under or over the land”. It is rare for this clause to be used used to cover archaeological works, but this may well be due to the fact that the use of planning conditions to cover the vast majority of archaeological works has – up until now – been unproblematic. The author knows of at least one case where a programme of archaeological works has been secured in this way, and it might be that in the future and where agreement of pre-commencement conditions cannot be reached, local authorities might consider the use of S.106 agreements as an alternative way of ensuring archaeological works are implemented.
The obvious downside of this approach is that S.106 agreements are also “agreements” between the client/developer and the local authority, in the same way that accepting a pre-commencement condition would be an agreement between these same two parties – presumably meaning that it would be as difficult to reach a consensus of opinion on one as it would the other. S.106 agreements are also considered generally less desirable as they take longer to negotiate, tend to be more onerous and of course are legally binding whereas conditions are not. However, in the altered planning landscape of the new requirements, these factors might well act as an advantage: the indication given by a local authority that it intends to seek an S.106 in the absence of any agreement on conditions, may help to change or soften an initially intransigent developer’s attitude towards a markedly less draconian and more flexible pre-commencement condition.
- Addressing the Archaeological Process: the Government View & Asking for the Applicant’s Agreement:
The Government intends to reduce the use of pre-commencement conditions as a result of this new measure, in order to reduce the amount of time it takes between a grant of planning permission being given and development commencing on site. There is no evidence that pre-commencement conditions are a cause of any delay other than anecdotal comment so it is questionable whether these measures are either warranted or can ever be successful. Nevertheless, the legislation is now in place so the framework has turned strongly against the use of pre-commencement conditions.
Worryingly, and even bearing in mind the discussions above, archaeology is one of the areas where their use seems unavoidable. Despite warnings and recommendations from the archaeological profession, the Government has refused to agree that there might be a problem in this particular regard. In cases where the use of pre-commencement conditions is still recommended, the main direction of the legislation is that the applicant be asked to agree the imposition of such a condition should planning permission be granted.
There is little information about how the process might work. Agreement could be sought through asking a fairly standard question:
The archaeological information contained within the Historic Environment Record and/or that you have provided as part of your application, indicates that remains of significance are likely to be present on the site, and their continued survival is threatened by the proposals you have submitted. Removal of archaeological remains is by necessity an operation that must be undertaken prior to development and should development be granted would require the use of a pre-commencement condition of the following suggested wording: “No development shall take place within the area indicated until the applicant, or their agents or successors in title, has secured the implementation of a programme of archaeological work in accordance with a Written Scheme of Investigation which has been submitted by the applicant and approved by the Planning Authority.”
Would you be willing to accept a pre-commencement archaeological condition attached to the planning permission, should the local authority be minded to grant it? Yes/No
Where the applicant agrees, the condition could be added as normal.
Where the applicant disagrees, comments or refuses to accept the suggested condition, it can not be imposed. In this situation the options available to the local authority would be:
i. Grant permission without the pre-commencement condition
ii. Seek written agreement to an alternative pre-commencement condition
iii. Refuse to grant permission (if it considers that the disputed pre-commencement condition is necessary to make the development acceptable).
In reality, and with reference to archaeology, these options are extremely limited.
Any planning condition still has to satisfy the standard “six tests” of being:
- Necessary,
- Relevant to planning,
- Relevant to the development in question,
- Enforceable,
- Precise and
- Reasonable
Therefore, if one is recommended, an archaeological condition could not and should not simply be cast aside and ignored if an applicant objects, as the first option suggests. Contrary to the opinion of certain recent (and inherently biased) commentators, archaeology is not a “nice to have” addition to the planning process, but an integral part of it. To ignore or remove conditions arbitrarily – in line with option i – would almost certainly result in the destruction of known archaeological remains in a fashion that would otherwise have been wholly avoidable. Not only is this prospect unacceptable in professional terms, it would also actually breach the fundamental guiding principles set out in the NPPF that development must be sustainable, as by definition unnecessary but wilful destruction of environmental information and/or fabric by development without mitigation or offsetting is contrary to sustainability. Any local authority that gains a reputation for failing to defend archaeological requirements within the planning process under this new system is likely to find itself subject to a regular series of judicial reviews and planning challenges.
The second option allows for the recommended condition to be reworded, either to make it a post-commencement condition (which the local authority could then impose without agreement), or suggest an alternative and presumably less-contentious pre-commencement condition wording for the applicant’s perusal and hopefully, agreement instead. As we have seen, archaeological mitigation is almost certainly likely to be a pre-commencement stage of work, and there are significant issues with attempting to reword archaeological conditions and still ensure that they satisfy the appropriate tests – it may just be unavoidable for a pre-commencement condition to be necessary even after prior assessment and evaluation. In this scenario the Government have not offered an opinion on what happens if the applicant continues to reject suggested and successive alternative pre-commencement conditions one after another as a matter of principle: presumably this carries on until either the applicant gets bored and accepts the condition, or the local authority gets equally bored and either approves the application without the condition or refuses it outright.
This leads to the third option available in the absence of any agreement on conditions between the applicant and the planning authority, which is for the application to be refused. The Government have outlined that they do not envisage there will be significant conflict in the new process, but they have left this option available to the local authority should consensus not be reached. In the case of archaeological mitigation which (certain watching briefs aside) must be conducted prior to development work commencing, it is inevitable that differing viewpoints on the need for and scope of archaeological investigation will arise during discussions, and that some applicants might use their new-found power in the planning decision-making process to try to “get away” with their archaeological obligations by refusing to accept pre-commencement conditions. In this case, refusal of the application entirely may well now be the only viable method of protecting archaeological remains within the planning process where agreement is not reached. Although not desirable, it is clear that where archaeological remains are concerned and the available options are to see them destroyed unrecorded (option i) destroyed unrecorded or at the wrong time where evidence will be lost (option ii) or not at all (option iii), that option iii – refusal – is the only alternative.
Conclusions:
Under scrutiny the new Regulations are revealed as a flabby and disorganised piece of legislation that is unlikely to work as effectively as the current system, and which seems to have taken little or no account of the technicalities involved in certain specialist areas of the planning process. Archaeology is not alone in being in this position of course; certain ecological investigations are similarly by definition pre-commencement activities, as are engineering works related to drains. A number of disciplines are now struggling to find a way to continue to practice reasonably within the new legislative landscape.
Nevertheless from 1st October 2018 onwards if a pre-commencement condition is required its use must be agreed with the applicant. Despite the misgivings of a number of planners, planning authorities and archaeologists about this process, it is clearly the case that the situation regarding archaeological conditions and planning should absolutely be business as usual. Despite recent claims to the contrary, archaeological advisors do not request nor recommend the use of archaeological conditions without good reason. Therefore they should continue to recommend their use in exactly the same way and using the same wording as previously, in order to best provide for the protection and sustainable management of the resource within the planning process. Planning authorities should expect to have to agree these recommendations with applicants, and they should (as the Government suggests) expect applicants to acquiesce to the use of the same conditions as they would have previously.
Of the Government’s proposed solutions to the possibility of conflict or ongoing non-agreement, only one – refusal of the application – is likely to be consistently acceptable. In essence, planning conditions are used to assist in the process of rendering an unacceptable proposal acceptable, so when a situation arises where no agreement is reached, the development is, by definition, unacceptable. This will however require the support of individual planning authorities – possibly at a stronger level than we’ve seen previously with regard to archaeological issues from some quarters, and might even necessitate the delivery of detailed technical guidance on the subject by Historic England to reinforce the planning position. It is recommended that local authorities should inform applicants – possibly even within the text of Local Plan policies – that where specialist study has revealed that a site does contain archaeological material, they recognise and endorse the need to conduct aspects of this work at the appropriate stages, that this might necessitate the use of a pre-commencement condition, and that they are fully prepared to respect the recommendations of their archaeological advisors and reject permission where agreement cannot be reached. It is also recommended that the planning and archaeological bodies should set up an ongoing mechanism to allow for applications refused on these particular administrative grounds to be reported, to ensure that the impact of the legislation on the development application process is being catalogued.
No alternative or supplementary solution to address the prospect of non-agreement by an applicant to accept a condition examined as part of this discussion is wholly satisfactory, and all have disadvantages. Local authority planners might soon find themselves faced with the prospect of having to consider refusing an application on archaeological grounds when all other issues have been resolved, or alternatively faced with the prospect of a long tussle with a developer to persuade them to accept a condition that they themselves (as a non-specialist) might not entirely understand the reason for imposing. On all counts, local authorities will need to ensure that their dialogue with the archaeological profession is deepened to ensure that advice and guidance is up-to-date and relevant, whilst the archaeological profession could similarly assist through simplifying or summarising its current guidance on such issues so it is easily intelligible to the unqualified planner or developer. Of the wider and supplementary options examined here, changing the wording of archaeological conditions so that they are not specifically “pre-commencement” in nature seems to be the most viable way to keep the archaeological planning process running as smoothly as it does now. There are inherent difficulties in this approach as we have seen – not the least of which are devising conditions which are actually enforceable in the first place, and which aren’t “pre-commencement by default” even if they don’t say “No development shall take place…”, but in the short term at least, this would appear to be the least-worst option.
Moving forward, it will become clear within the next few years whether or not the legislation is as inconsequential as the Government indicate they have envisaged (in which case why bother introducing it?), or whether it will be as disruptive as is feared by many. The actuality might well lie somewhere in the middle, but this is not a welcome or enticing prospect and it is likely that, as a result of this measure, the country will lose archaeological sites to development unrecorded. It is recommended that any and all groups interested in the archaeological resource either with a national or geographical remit should ensure that they are diligent in monitoring what happens in their area, and maintain good and friendly links with the relevant archaeologists and planning departments. It may just be that the position of archaeology within the planning process is on the cusp of a serious and detrimental change: we all need to ensure that we’re watching to see this doesn’t happen.
References.
Town and Country Planning Act: Statutory Instrument no. 566: Pre-commencement conditions (2018)
http://www.legislation.gov.uk/uksi/2018/566/made
Town and Country Planning Act, (1990) Section 106
https://www.legislation.gov.uk/ukpga/1990/8/section/106
Good Practice Advice note 2, Managing Significance in Decision-Taking in the Historic Environment https://content.historicengland.org.uk/images-books/publications/gpa2-managing-significance-in-decision-taking/gpa2.pdf/
Chartered Institute for Archaeologists’ Joint Statement with the Council for British Archaeology and Association of Local Government Archaeological Officers, on recent Government reform announcements (2017)
“The Housing Problem in London” (2017) a report by Sir Mark Boleat
https://www.boleat.com/materials/housing_2017.pdf
Circular 11/95: The Use of Conditions in Planning Permission
Government Guidance on the use of planning conditions
https://www.gov.uk/guidance/use-of-planning-conditions
The Revised National Planning Policy Framework (2018)
Government response to the consultation on Improving the Use of Planning Conditions (2018)