Metropolitan Open Land and its Green Belt equivalence

Metropolitan Open Land is a London development plan designation that attracts Green Belt level protection without being Green Belt. Policy G3 of the London Plan 2021 states that it should be afforded the same protection as Green Belt, and that inappropriate development should be refused except in very special circumstances. The practical consequence for a consultant is that the national Green Belt exception categories and the very special circumstances test apply by policy adoption rather than by national designation, and the arguments that have developed around Green Belt reform do not transfer automatically.

That distinction is where most of the useful work is. Get it wrong and you build a case on a policy that does not apply to your site.

What Metropolitan Open Land protects

The designation exists because much of London's open land sits inside the built-up area rather than around it, so Green Belt, which works outward from an urban edge, cannot protect it. Metropolitan Open Land protects strategically important open space within the city.

In practice that means a wide range of land types carry the designation: large parks and commons, playing fields and sports grounds, cemeteries, allotments, reservoirs and filter beds, golf courses, and river corridors. Some of it is previously developed. Some of it is not publicly accessible. Neither fact weakens the designation.

Boroughs designate it through their local plans, and the London Plan sets the framework. So two things have to be checked for any site: the borough's policies map and development management policy, and Policy G3 itself. The borough policy will sometimes be more specific about what it will accept.

Why it attracts Green Belt level protection

Policy G3 imports the protection rather than reproducing the policy. The effect is that development on Metropolitan Open Land is tested in the same way as development in the Green Belt: is it inappropriate development, and if so are there very special circumstances that clearly outweigh the harm.

The exception categories in national policy therefore matter. Buildings for agriculture and forestry, appropriate facilities for outdoor sport and outdoor recreation, limited extensions or alterations to existing buildings, replacement buildings not materially larger, limited infilling, and the redevelopment of previously developed land in defined circumstances all carry across. The current National Planning Policy Framework, published on 17 August 2026, organises these by policy code rather than paragraph number, so confirm the code on gov.uk before citing it in a statement. Do not copy a paragraph number from an older document, because the Framework was renumbered in December 2024 and recoded again in 2026.

The point consultants miss is what does not carry across. Green belt specific reforms, including the grey belt concept introduced for Green Belt land in the December 2024 Framework, operate on Green Belt as nationally defined. Metropolitan Open Land is not Green Belt, so a grey belt argument does not automatically apply to it, and advancing one without addressing that gap invites a short answer from the authority. Check the current wording of both the Framework and Policy G3 before deciding how to run the point.

The criteria for designating land

Policy G3 sets out the basis on which land qualifies, and the criteria are worth knowing because they also shape how harm is assessed. Land should meet at least one of the following.

1. It contributes to the physical structure of London by being clearly distinguishable from the built-up area.
2. It includes open air facilities, especially for leisure, recreation, sport, the arts and cultural activities, which serve either the whole or significant parts of London.
3. It contains features or landscapes of either national or metropolitan value, whether historic, recreational or related to biodiversity.
4. It forms part of a strategic corridor, node or link in the network of green infrastructure and meets at least one of the above.

Identify which criterion your site was designated for. A playing field designated for its metropolitan sporting function is harmed differently by a building than a river corridor designated for its green infrastructure role, and an argument pitched at the wrong criterion reads as generic.

Boroughs do not always record the reason, and the local plan examination documents are often the only place it is explained. Those documents are worth the hour it takes to find them.

Inappropriate development and the exceptions

Most applications on Metropolitan Open Land fall into one of three patterns, and each has a familiar shape.

Sports and recreation facilities. Pavilions, changing rooms, floodlights and artificial pitches often fall within the outdoor sport and recreation exception, provided the facility is appropriate in kind and preserves openness. Scale is the usual issue: a clubhouse with a function room and a bar stops being a facility for outdoor sport at some point, and the application has to deal with that honestly.

Extensions and replacements. These are tested on whether the extension is limited or the replacement materially larger, measured against the original building. Keep the baseline measurement defensible, with a schedule of existing and proposed volumes and footprints, because the argument is almost always about the comparison rather than the policy.

Redevelopment of previously developed land. Where a site within Metropolitan Open Land carries redundant buildings, the exception can apply, but it depends on the effect on openness and on the purposes of including the land in the designation. The stronger cases are those that reduce built footprint or consolidate development on part of a site while opening up the rest.

Where none of the exceptions applies, the case is a very special circumstances case, and it has to be built as one: identify the harm precisely, identify the benefits precisely, and explain why the benefits clearly outweigh the harm. A Planning Statement that sets the balance out in those terms is the document the committee report will be drawn from.

Openness assessment on a designated site

Openness is not a volumetric calculation, and treating it as one weakens an assessment. The courts have held that openness has both spatial and visual dimensions, and the Supreme Court in Samuel Smith Old Brewery confirmed that whether visual impact is taken into account is a matter of planning judgement rather than a point of law.

For Metropolitan Open Land, the visual dimension often matters more than on peripheral Green Belt, because the sites are smaller, enclosed by development and experienced from close range. A single storey building set against an existing boundary wall can have minimal effect on openness. The same building in the centre of a field reads very differently.

Evidence that helps, in rough order of usefulness. A verified view study from the publicly accessible points from which the land is experienced. A plan showing existing built footprint, proposed footprint and the change. Sections showing the proposal against the existing enclosure. And a straightforward account of what is visible from where, in daylight and after dark if lighting is proposed. On larger sites that becomes a Landscape and Visual Impact Assessment following the recognised landscape assessment guidance.

Where the designation rests on a recreational or sporting function, an Open Space Assessment addressing quantity, quality and accessibility is usually needed alongside, because loss of function is a harm separate from loss of openness.

Boundary alterations through plan making

Metropolitan Open Land boundaries cannot be altered through a planning application. They change through the local plan process, and Policy G3 expects alterations only where justified in exceptional circumstances through a plan review.

So the strategic route for a landowner who believes land is wrongly designated is to engage with the borough's local plan, with evidence addressing the designation criteria, at the call for sites or regulation 18 stage. That is a slow route, and the honest position is that de-designation succeeds rarely.

An application made on the basis that the land does not merit the designation, without a plan review, runs into section 38(6) of the Planning and Compulsory Purchase Act 2004: the determination must be made in accordance with the development plan unless material considerations indicate otherwise, and the designation is part of the plan. The argument can be made as a material consideration, and it will carry limited weight on its own.

Checking the designation for a site

Four checks, in this order. The borough's adopted policies map, which is the definitive record. The borough's development management policy on Metropolitan Open Land, which may add local requirements. Policy G3 of the London Plan for the strategic framework. And the national datasets for the surrounding designations, because Metropolitan Open Land frequently overlaps conservation areas, local wildlife sites, flood zones and registered parks, each of which brings its own test.

Overlapping designations are the norm rather than the exception, and a statement that deals with the open land policy while ignoring a coincident heritage designation will be found out. The approach is the same discipline needed for industrial land and the no net loss policy and for sites inside an opportunity area allocation, where strategic and local designations have to be read together.

This is general guidance about the London planning system, not legal advice. Designation boundaries and policy wording change, so check the position with the relevant borough or a qualified planning professional before relying on it.

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