Mayoral referral thresholds for London residential schemes
A residential scheme of more than 150 units in Greater London must be referred to the Mayor. The two stage process, the powers that apply at each, and the documents the Greater London Authority expects.
The mayor of london referral threshold that matters most for housing is 150 units. A residential scheme in Greater London providing more than 150 houses or flats is of potential strategic importance under the Town and Country Planning (Mayor of London) Order 2008, which means the borough cannot decide it without referring it to the Mayor first. Referral is not a second application and it is not an appeal. It is a statutory stage that runs alongside the borough's own process, and it changes the evidence base, the programme and sometimes the affordable housing offer.
Boroughs remain the decision maker on most referable schemes. The Mayor's powers bite at two moments, and knowing which one you are in tells you what can still be negotiated.
What referral means in practice
Referral is triggered by the development, not by the borough's view of it. Once an application falls within a category in the Order, the borough must send it to the Greater London Authority before resolving to grant or refuse, and must send it again after that resolution.
At the first stage the Mayor issues a report stating whether the application complies with the London Plan and what would need to change for it to do so. That report is a material consideration and boroughs take it seriously, partly because the second stage gives the Mayor teeth.
The practical effect for an applicant is that two planning authorities are reading the submission against two policy documents. The borough is applying its local plan. The GLA is applying the London Plan. Where the two pull in different directions, the application has to answer both, and a submission written only for the borough will read as incomplete at City Hall.
The categories that make a scheme referable
The residential category is the clear one. More than 150 houses, flats, or houses and flats makes a scheme referable anywhere in Greater London. Mixed-use schemes count the residential element for this purpose, so a commercial-led scheme with a substantial housing component can be referable on the housing alone.
The Order also sets floorspace categories, with different figures inside the City of London, elsewhere in central London and outside central London, and it sets height categories with a lower trigger for buildings adjacent to the River Thames and a much higher one inside the City of London. Further categories cover development on Green Belt and Metropolitan Open Land, certain waste and minerals development, and proposals that conflict with the development plan in defined ways.
Read the current text of the Order before assuming a scheme is below the line. It has been amended, the categories are drafted with specific geographies attached, and a scheme at 149 units with a tall element or a Thames frontage can still be referable on another category.
Height and site-specific triggers
Height is measured to the top of the building and the thresholds are geographic rather than uniform. A building near the Thames triggers referral at a far lower height than the same building in the City of London, which reflects the strategic views and the river prospect policies in the London Plan rather than any structural concern.
Site-specific triggers matter on constrained sites. Green Belt and Metropolitan Open Land, strategic industrial locations, protected wharves and land in a strategic view corridor all bring their own referral routes or GLA interest. On those sites the referral question should be settled in the first week of the project, because it changes who you are designing for.
The two stage process and its timing
- Stage one. The borough refers the application on receipt. The Mayor has six weeks to issue a report on London Plan compliance. This is where design, affordable housing, energy, carbon, fire safety and transport issues are set out, and where the GLA officers ask for changes.
- The borough's determination. The planning committee or delegated officer resolves to grant or refuse, taking the stage one report into account.
- Stage two. The borough refers the application back with its resolution. The Mayor has 14 days to allow the borough to determine the application, direct refusal, or direct that he will act as the local planning authority for the application.
Where the Mayor takes over, the application is determined by City Hall, usually after a public representation hearing, and the borough becomes a consultee on its own patch. That is the part boroughs dislike, and it is rare compared with the number of referrals.
What the Mayor can and cannot do
The Mayor can direct a borough to refuse. He can take over an application and grant it himself. He cannot simply direct a borough to grant permission, which is why call-in is the route used when the Mayor wants a scheme approved against a borough's resolution to refuse.
Two further limits are worth holding onto. The Mayor cannot impose conditions on an application the borough determines, so the changes sought at stage one have to be negotiated into the borough's own recommendation. And the stage two window is short, so a scheme that only reaches agreement at committee leaves no room for further movement.
Preparing for stage one
GLA officers read a defined set of documents and expect them in a recognisable form. Five carry most of the weight on a residential scheme.
Affordable housing comes first. The London Plan's threshold approach sets the level at which a scheme can follow the fast track route without a viability assessment, with a higher level on public sector and industrial land. Where the offer falls below it, a full viability assessment and review mechanisms follow, and the scheme will be scrutinised by the GLA's own advisers. The Affordable Housing Statement has to set out tenure split, unit mix and the route being taken, not just a percentage.
Energy comes second, structured to the be lean, be clean, be green, be seen hierarchy with a carbon offset payment where the on-site target is not met. The scaling of that evidence with scheme size is covered in energy and carbon evidence by scheme size.
Whole life carbon comes third. Referable applications need a Whole Life Carbon Assessment completed on the GLA's template, reported by lifecycle module, with a post-construction update.
Circular economy comes fourth, through a Circular Economy Statement covering material choices, reuse and end of life.
Fire safety comes fifth. The London Plan has its own fire safety policy, and where the building is a relevant building a Fire Statement is required with the application under the Development Management Procedure Order. That document must be prepared by someone with the necessary fire engineering competence, so an AI-assisted draft is a starting point for that professional rather than a substitute.
Alongside those, expect urban greening, play space, transport modelling, and a design review at an early stage.
Where referral changes the strategy
Three decisions look different once a scheme is referable.
Unit numbers stop being a purely commercial choice. A scheme at 140 units and a scheme at 160 units carry different evidence costs, different programme risk and a different negotiating counterparty, and the gap is not linear.
Pre-application engagement becomes double. Boroughs and the GLA both offer pre-application services, and the GLA meeting is the one that tells you whether the affordable housing route is credible. Skipping it saves a fee and costs months.
And the affordable housing position has to be settled before the design is fixed, because the tenure split drives core arrangements, unit mix and the viability case together. Retrofitting an increased affordable offer into a designed scheme is where most referable applications lose time.
Enter your postcode on PlanScope to see which reports a London residential scheme is likely to need.
This article is general guidance, not legal advice. The referral categories and the London Plan are amended from time to time, so check the current text and the position with the borough or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
At how many homes does a London scheme become referable to the Mayor?
More than 150 houses, flats, or houses and flats anywhere in Greater London makes an application of potential strategic importance under the Town and Country Planning (Mayor of London) Order 2008. Mixed-use schemes count the residential element for this purpose. Other categories based on floorspace, height and site designation can catch smaller schemes.
Can the Mayor of London refuse my application?
The Mayor can direct the borough to refuse at stage two, or direct that he will act as the local planning authority and determine the application himself. He cannot direct a borough to grant permission, which is why taking over an application is the route used where the Mayor supports a scheme the borough has resolved to refuse.
How long do the referral stages take?
The Mayor has six weeks from referral at stage one to issue a report on London Plan compliance. After the borough resolves to grant or refuse it refers the application back, and the Mayor has 14 days at stage two to allow the borough to determine it, direct refusal, or take it over. Plan the programme around both windows.
Does a referable scheme need different supporting documents?
It needs the borough's validation list plus the documents the London Plan requires. On a residential scheme that usually means an affordable housing statement setting out the threshold route, an energy assessment structured to the be lean, be clean, be green, be seen hierarchy, a whole life carbon assessment on the Greater London Authority template, a circular economy statement and fire safety information.
Is height alone enough to trigger referral?
Yes, on the height categories in the Order. The trigger is geographic rather than uniform, with a far lower height threshold for buildings adjacent to the River Thames and a much higher one inside the City of London. A scheme below the residential threshold can still be referable on height, floorspace or site designation.
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.