National Park purposes in development decisions
National Park authorities work to two statutory purposes, and conservation wins where they cannot be reconciled. Here is how that plays out in development management and what evidence to bring.
A National Park authority deciding a planning application is working to two statutory purposes that do not carry equal weight. Section 5 of the National Parks and Access to the Countryside Act 1949, as substituted by the Environment Act 1995, sets them out: conserving and enhancing the natural beauty, wildlife and cultural heritage of the area, and promoting opportunities for public understanding and enjoyment of its special qualities. Where the two cannot be reconciled, section 11A(2) of the 1949 Act requires greater weight to be given to conservation. That provision is what planners call the Sandford Principle, and it decides a surprising number of applications for tourism, recreation and access proposals inside a park.
If your proposal is about getting people into the park, expect to be asked how it conserves what they have come to see.
The statutory purposes and the order between them
The purposes are not a hierarchy in ordinary circumstances. A park authority is expected to pursue both, and most decisions involve no conflict at all: a farm building, a house extension, a village shop.
The order only emerges where the purposes pull against each other. A new car park that opens up a remote valley to visitors serves the second purpose and damages the first. A mountain bike trail network, a glamping site on an exposed ridge, a visitor centre on open moorland: all of these are enjoyment proposals with conservation costs, and the 1949 Act tells the decision maker which way to lean.
Section 11A(1) adds a third element that is often overlooked. In pursuing the purposes, the authority must seek to foster the economic and social wellbeing of local communities, though that is expressly not a purpose in its own right and cannot be used to outweigh conservation on its own.
How a conflict between purposes is resolved
The test bites only on an irreconcilable conflict, and that word does real work. An authority will look first at whether design, scale, siting or management can remove the conflict, and will refuse to accept that it is irreconcilable while an obvious alternative exists.
That is where most applications are won or lost. Three moves tend to work:
- Move the development. Siting a car park behind existing woodland rather than on the open valley floor can take the conflict away entirely.
- Reduce it. Fewer pitches, a smaller building, a shorter access track, lower lighting columns.
- Manage it. A seasonal restriction, a visitor management plan, a limit on numbers, or habitat works secured by condition or by a section 106 agreement.
Only when none of those work does the authority reach for section 11A(2), and at that point the answer is usually refusal. Arguing the enjoyment purpose harder does not help, and the detailed reasoning is set out in National Parks and the statutory purposes test.
There is an honest uncertainty here worth naming. Authorities vary in how early they conclude that a conflict is irreconcilable, and two officers looking at the same glamping proposal can reasonably differ on whether a reduced scheme is a real alternative or a fiction.
The duty on other bodies, and what changed in 2023
The purposes do not bind only the park authority. Section 11A(2) applies to any relevant authority exercising functions that affect land in a National Park, which takes in the county council as highway authority, the water undertaker, the Environment Agency and neighbouring councils deciding applications just outside the boundary.
The wording of that duty was strengthened by the Levelling-up and Regeneration Act 2023, moving relevant authorities from having regard to the purposes towards seeking to further them. As at 2026 that is the operative formulation, and it matters for applicants because it gives you an argument to make to bodies that historically treated the park as somebody else's problem. Check the current text on legislation.gov.uk before relying on the precise words.
Development just outside a boundary is caught too. A wind turbine, a large shed or a lighting scheme on adjoining land can harm the setting of the park, and the host authority has to engage with the purposes even though the site is outside the designation.
What a park authority's local plan usually says
Park authorities are local planning authorities for their areas and prepare their own local plans, which is the practical starting point for any application. National Park authorities as the planning authority covers the institutional side.
The policy content follows a recognisable pattern. Expect a strategic policy restating the purposes, a design and materials policy far more prescriptive than a lowland district would attempt, a housing policy tying new dwellings to local occupancy or affordable need, a policy on conversion of traditional farm buildings, a dark skies or external lighting policy, and a policy restricting development that would harm tranquillity or the perception of remoteness.
The National Planning Policy Framework (edition of 17 August 2026) gives National Parks, the Broads and National Landscapes the highest status of protection in relation to scenic beauty, and restricts major development in them to exceptional circumstances where it is in the public interest. Check the relevant policy code in the current edition, because the Framework was re-organised into policy-coded chapters in August 2026 and the older paragraph numbers no longer apply.
Major development in that policy sense is not defined by unit numbers. The authority judges it on scale and character in the context of the designation, so a scheme that would be modest elsewhere can be major here.
Householder work and the permitted development differences
National Parks are article 1(5) land under the Town and Country Planning (General Permitted Development) (England) Order 2015, which strips out several householder rights:
- Side extensions under Class A are not permitted development.
- Rear extensions of more than one storey are excluded.
- Cladding an elevation with stone, tiles, render or timber is not permitted.
- Outbuildings under Class E are limited to 10 m2 where they sit more than 20 metres from any wall of the house.
- Solar equipment and other Part 14 rights carry extra siting conditions.
Agricultural rights are narrower as well. National Parks are also article 1(6) land, so Part 6 rights for agricultural buildings and excavations carry additional restrictions and a wider requirement to apply for prior approval of siting, design and external appearance.
Anyone buying land inside a park should check the designation and the Article 4 position together with everything else, and checking a site for constraints before you make an offer sets out the sequence.
| Proposal | Outside a park | Inside a National Park |
|---|---|---|
| Single-storey side extension | Often permitted development | Needs permission |
| Render or timber cladding | Often permitted development | Needs permission |
| Outbuilding over 20 m from house | Up to 50 per cent of curtilage area | Limited to 10 m2 |
| New agricultural building | Prior notification in many cases | Wider prior approval requirement |
Evidence on scenic quality and dark skies
Two evidence types carry disproportionate weight in park decisions. The first is visual: how the proposal reads from public vantage points, in winter as well as summer, and at the distances people actually experience the site from. A Landscape and Visual Impact Assessment prepared to GLVIA3 is the standard vehicle, and park authorities expect a suitably qualified author, with professional review strongly advised even where the policy does not name a competence standard.
The second is lighting. Tranquillity and night sky quality are part of the special qualities the purposes protect, and several English parks hold dark sky designations that bring tight external lighting expectations. Design to the lowest environmental zone in the Institution of Lighting Professionals guidance on obtrusive light, specify colour temperature and upward light ratio on the drawings, and offer a condition requiring no external lighting beyond what is shown. That single condition removes a common reason for refusal.
Talking to the authority before you apply
Park authorities are small, and their officers know their patch in detail. A pre-application discussion is worth more here than in a large unitary authority, because the officer can often tell you in one meeting whether the principle is acceptable and what the materials palette needs to be.
Bring a site plan, photographs from the public rights of way nearest the site, and an honest statement of what the proposal is for. Ask specifically whether the officer sees a conflict between the two purposes in your case, because the answer shapes everything else you do.
You can draft the planning statement, design narrative and supporting reports for a National Park application in PlanScope and send them for professional review before submission. Browse all 66 PlanScope report types at the report index and start with the one the authority has asked for.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required. This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it.
Frequently asked questions
What are the two National Park purposes?
Section 5 of the National Parks and Access to the Countryside Act 1949, as substituted by the Environment Act 1995, sets them as conserving and enhancing natural beauty, wildlife and cultural heritage, and promoting opportunities for public understanding and enjoyment of the area's special qualities. A separate duty in section 11A(1) requires authorities to support the economic and social wellbeing of local communities while pursuing those purposes.
What is the Sandford Principle?
It is the rule in section 11A(2) of the 1949 Act that where the two National Park purposes cannot be reconciled, greater weight goes to conserving and enhancing natural beauty, wildlife and cultural heritage. It applies only to an irreconcilable conflict, so an authority will first test whether siting, scale or management can remove the conflict altogether.
Does the duty apply to bodies other than the park authority?
Yes. Section 11A(2) reaches any relevant authority whose functions affect land in a National Park, including the highway authority, water undertakers, the Environment Agency and neighbouring councils deciding applications close to the boundary. The Levelling-up and Regeneration Act 2023 strengthened that duty towards seeking to further the purposes rather than merely having regard to them.
Which permitted development rights are removed in a National Park?
National Parks are article 1(5) land under the GPDO 2015, so side extensions, rear extensions of more than one storey and cladding an elevation are all excluded, and outbuildings more than 20 metres from the house are limited to 10 square metres. Parks are also article 1(6) land, which widens the prior approval requirement for agricultural buildings.
What counts as major development in a National Park?
It is judged on scale and character in the context of the designation rather than by a unit or floorspace figure, so a scheme that would be modest in a lowland district can be major inside a park. National policy restricts such development to a narrow set of circumstances where it is in the public interest, and the authority decides whether the threshold is crossed.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.