8.1 The National Planning Policy Framework

The UK National Planning Policy Framework (2012, revised 2018 and 2019) (NPPF) has replaced previous policy guidance. Its underlying principle is to enable the planning system to contribute to the achievement of sustainable development (NPPF paragraph 7).

The importance of conserving heritage assets is recognised in the NPPF as one of three objectives in achieving sustainable development (NPPF Para 8c) – i.e. ‘to contribute to protecting and enhancing our natural, built and historic environment’.

The revised NPPF clearly sets out that World Heritage Sites are assets of the highest significance.  Indeed, the opening paragraph of Section 16 of the revised NPPF states: “Heritage assets range from sites and buildings of local historic value to those of the highest significance, such as World Heritage Sites which are internationally recognised to be of Outstanding Universal Value”.

Paragraph 184 states: “heritage assets are an irreplaceable resource”. This resource, if lost within a World Heritage Site, can lead to the Site being placed on UNESCO’s World Heritage in Danger List, and if the damage is not reversed, can lead to deletion from the World Heritage List.

Paragraph 193 adds that “great weight should be given to the asset’s conservation (and the more important the asset the greater the weight should be).  This is irrespective of whether any potential harm amounts to substantial harm, total loss or less than substantial harm to its significance”.

Paragraph 194 goes on to say: “Any harm to, or loss of, the significance of a designated heritage asset (from its alteration or destruction, or from development within its setting), should require clear and convincing justification. Substantial harm to or loss of:

a) grade II listed buildings, or grade II registered parks or gardens, should be exceptional;

b) assets of the highest significance, notably scheduled monuments, protected wreck sites, registered battlefields, grade I and II* listed buildings, grade I and II* registered parks and gardens, and World Heritage Sites, should be wholly exceptional.”

Paragraph 196 of the National Planning Policy Framework states: “Where a development proposal will lead to less than substantial harm to the significance of a designated heritage asset, this harm should be weighed against the public benefits of the proposal including, where appropriate, securing its optimum viable use.”

Paragraph 200 states that local planning authorities should look for opportunities for new development within Conservation Areas and World Heritage Sites and within the setting of heritage assets, to enhance or better reveal their significance.

Paragraph 201 of the NPPF notes that not all elements of a World Heritage Site will necessarily contribute to its significance. Nevertheless, overall, the WHS represents an asset of very high value.

Local harm should not be under-rated when considering the effect on the WHS as a whole. It should not lie below that of a similar effect on a much smaller world heritage site, otherwise such reasoning could lead to the proliferation of similar harm throughout the WHS.3

From this criteria, it is clear that planning authorities must assess an application’s ability to contribute to the achievement of sustainable development, against negative impacts to heritage assets of the highest recognised significance. Significance can be harmed or lost through alteration or destruction of the heritage asset or development within its setting. As heritage assets are irreplaceable, any harm to or loss should require clear and convincing justification.  This assessment can best be done through a Heritage Impact Assessment (HIA) (see 1.8.2).

The National Planning Policy Framework (NPPF) touches on this methodology in paragraph 189: “In determining applications, local planning authorities should require an applicant to describe the significance of any heritage assets affected, including any contribution made by their setting. The level of detail should be proportionate to the assets’ importance and no more than is sufficient to understand the potential impact of the proposal on their significance.”  However, it has to be stated that the current UK planning legislation does not fully align with the terminology set out by UNESCO, or provide the level of protection UNESCO wishes to see. One particular concern is in the use of the terms ‘substantial harm’ and ‘less than substantial harm’, a two-term system, in which the latter can be easily misunderstood as being ‘acceptable harm’.  Any level of harm is still harm and UNESCO will be concerned about any action that impacts on Outstanding Universal Value. This is particularly the case where small actions cumulatively erode the OUV of the World Heritage Site.

The Ministry for Housing Communities and Local Government (MHCLG) Planning Practice Guidance (see 1.8.3 below) paragraph 31 explains the differences in terminology between UK legislation and UNESCO’s: “The international policies concerning World Heritage Sites use different terminology to that in the National Planning Policy Framework. World Heritage Sites are inscribed for their ‘Outstanding Universal Value’ and each World Heritage Site has defined its ‘attributes and components’ the tangible remains, visual and cultural links that embody that value. The cultural heritage within the description of the Outstanding Universal Value will be part of the World Heritage Site’s heritage significance and National Planning Policy Framework policies will apply to the Outstanding Universal Value as they do to any other heritage significance they hold. As the National Planning Policy Framework makes clear, the significance of the designated heritage asset derives not only from its physical presence, but also from its setting.”

Local planning authorities need to have policies in their local plans that reference their commitment to the WHS and its management plan.

3 Taken from paragraph 36 of the report by Inspector Alan Novitzky BArch(Hons) MA(RCA) PhD RIBA dismissing a planning appeal at Darley Abbey for residential development in the buffer zone (appeal references APP/C1055/W/15/3137935 and APP/C1055/W/15/3141117) in July 2016.

Belper mills from the Chevin hillside

8.2 Heritage Impact Assessments

The UNESCO World Heritage Committee wishes to ensure Heritage Impact Assessments are undertaken whenever there are specific potential impacts on Outstanding Universal Value within an application. HIAs are needed in assessing projects, including an assessment of cumulative impacts, and these should be submitted before any final decision is taken. The UK’s Department of Digital, Culture, Media and Sport also wishes to see Historic Impact Assessments undertaken as they represent good practice. The World Heritage Committee favours the ICOMOS Heritage Impact Assessment methodology, which can be found at  http://www.icomos.org/world_heritage/HIA_20110201.pdf.

Following this methodology, and particularly the structure set out within Appendix 4 of the document, enables an assessment of impact specific to the attributes of OUV and to OUV overall to be made. A key element of these guidelines is the desirability of an initial scoping exercise. Where the development proposals clearly have little or no impact on OUV there is no need for an HIA. At the other end of the spectrum applications that have the potential to impact significantly on OUV would usually merit the full HIA treatment as set out in Appendix 4 of the guidance. ICOMOS suggests in the latter cases there should be a section on World Heritage in the Environmental Impact Assessment (or design and access statement or heritage statement) summarising the key points, with the HIA itself attached as a technical appendix.

As well as providing the means to avoid or mitigate harm to OUV, another reason the UNESCO World Heritage Committee wishes to see the standard methodologies, advocated by its advisory bodies, used widely so that like can be compared with like in World Heritage Sites across the world. This will enable key issues and trends to be identified and policy to be developed accordingly.  Applicants need to be advised to undertake this type of assessment in cases that merit it rather than a visual impact assessment on its own.

8.3 Ministry of Housing, Communities & Local Government Planning Practice Guidance

HM Government’s Planning Practice Guidance (PPG) paragraph 26 sets out that “effective management of World Heritage Sites involves the identification and promotion of positive change that will conserve and enhance their Outstanding Universal Value, authenticity, integrity and with the modification or mitigation of changes which have a negative impact on those values.”

This guidance sets out specific principles, in paragraph 32, which local planning authorities should aim to meet when developing World Heritage-related policies. These are the following aims:

  • protecting the World Heritage Site and its setting, including any buffer zone, from inappropriate development;
  • striking a balance between the needs of conservation, biodiversity, access, the interests of the local community, the public benefits of a development and the sustainable economic use of the World Heritage Site in its setting, including any buffer zone;
  • protecting a World Heritage Site from the effect of changes which are relatively minor but which, on a cumulative basis, could have a significant effect;
  • enhancing the World Heritage Site and its setting where appropriate and possible through positive management;
  • protecting the World Heritage Site from climate change but ensuring that mitigation and adaptation is not at the expense of integrity or authenticity.
  • It adds: “Planning authorities need to take these principles and the resultant policies into account when making decisions.”

The protection of the setting of this World Heritage Site is particularly important, because of the critical significance to the Property’s OUV of the location of the mills and their associated settlements, within a rural landscape, arrested in time. Because it is of vital importance to the maintenance of the Property’s OUV for the setting to remain rural, the respective local planning authorities have adopted policies to ensure the protection of this setting. In order to assist clarity as to what constitutes the immediate setting of the DVMWHS’s setting a Buffer Zone has been defined (see 5.4, page 28) and endorsed by UNESCO.  Paragraph 33 of HM Government’s Planning Practice Guidance defines the Buffer Zone as “an area surrounding the World Heritage Site which has complementary legal restrictions placed on its use and development to give an added layer of protection to the World Heritage Site. The buffer zone forms part of the setting of the World Heritage Site.”

Paragraph 33 continues: “It may be appropriate to protect the setting of World Heritage Sites in other ways, for example by the protection of specific views and viewpoints.” The Derwent Valley Mills World Heritage Site has identified 50 monitoring views to help with this process, but because of the size and complexity of the Derwent Valley Mills site it would be almost impossible to provide a definitive set of views. Those identified are therefore only indicative of the types of view which are important to the protection of the DVMWHS. They can be found on the Derwent Valley Mills World Heritage Site website http://www.derwentvalleymills.org.

Historic England provides advice on a number of relevant topics:

• Advice Note 12 relating to ‘Statements of Heritage Significance’ can be found at https://historicengland.org.uk/images-books/publications/statements-heritage-significance-advice-note-12/

• Publication ‘Historic Environment Good Practice Advice in Planning 3’ (2nd Edition) can be found at https://historicengland.org.uk/images-books/publications/gpa3-setting-of-heritage-assets/

• Advice Note 3 relating to ‘The Historic Environment and Site Allocations in Local Plans’’ can be found at https://historicengland.org.uk/images-books/publications/historic-environment-and-site-allocations-in-local-plans/

8.4 Statutory controls

A comprehensive system of statutory control operates under the provisions of the Town and Country Planning Act (1990) and the Planning (Listed Buildings and Conservation Areas) Act (1990).  A network of strategic planning policies is also in place to protect the Property and its setting. There are thirteen Conservation Areas falling wholly or partly within it. 859 buildings within the Property and Buffer Zone are included on the List of Buildings of Special Architectural or Historical Interest.  There are also 13 Scheduled Monuments.

8.5 Procedure for reporting on intent to harm Outstanding Universal Value

If a local planning authority is minded to approve an application that has been highlighted by Historic England and/or the Derwent Valley Mills World Heritage Site Partnership as likely to negatively impact on the Outstanding Universal Value of the World Heritage Site, then, as set out within Paragraph 172 of the Operational Guidelines for the Implementation of the World Heritage Convention (UNESCO, 2017), the planning authority and the DVMWHS Partnership should inform Henry Owen-John (henry.owen-john@historicengland.org.uk), Historic England’s Head of International Advice and Enid Williams (enid.williams@culture.gov.uk), Senior Heritage Policy Adviser at the Department of Digital, Culture, Media and Sport (DCMS), at the earliest possible occasion. They will then decide whether to inform UNESCO’s World Heritage Centre.

8.6 Appeal decisions

In recent years a number of Planning Appeals have taken place in the Derwent Valley Mills and other World Heritage Sites, which have been refused on World Heritage grounds, or World Heritage issues have been major considerations as part of a refusal.

Often, the impact on the World Heritage Site’s Outstanding Universal Value has constituted, in NPPF terms, ‘less than substantial harm’. In the majority of cases this has been sufficient to dismiss appeals as World Heritage Sites are heritage assets of the highest significance. There has also been an acknowledgement by HM Inspectors that the incremental impact of ‘less than substantial harm’ could, in certain cases, accrue into substantial harm (this is supported by HM Government’s Planning Practice Guidance 9 which endorses the principle of protecting a World Heritage Site from the effect of changes which are relatively minor but which, on a cumulative basis, could have a significant effect).

Appendix 11 sets out the parts of the inspectors’ statements that the World Heritage Site Partnership believes are useful precedents for future planning decisions and appeals. Headings have been provided to indicate themes.