The Mayor becomes involved when an application falls within a statutory category of potential strategic importance, not simply because the site is in London. From 11 May 2026, a new category covering 50 or more houses or flats widened notification. Schemes caught only by that category follow a different process from other referable applications. [1][2][3]
Check the statutory category first
The Mayor of London Order identifies categories by matters including housing numbers, building scale and particular land designations. The established housing category, Category 1A, covers more than 150 homes. Other categories can catch a proposal independently of its dwelling count. Consequently, “fewer than 151 homes” is not a sufficient referral assessment. [1]
The new Category 3J is important for schemes of 50 homes upwards. However, its special procedure applies only when the proposal is referable solely through that category. A 50-home development also caught by another statutory category cannot assume that it receives the Category 3J-only procedure. [2]
Ask the project team to record every potentially relevant category, the measurements used and the application dates. This is a practical way of avoiding a housing-count check that overlooks another reason for referral. [1][2]
The established two-stage procedure
For applications following the ordinary referral procedure, the borough first supplies the application to the Mayor. The Order provides for a statement within six weeks on compliance with the spatial development strategy. This initial involvement is not the final decision on the application. [1]
Before determination, the borough supplies the required further material. The ordinary standstill is 14 days, measured from the receipt date notified in writing by the Mayor, unless the Mayor releases the application earlier. Depending on the statutory powers and tests, the Mayor can allow the borough to determine it, direct refusal or take over its determination. [1]
What is different for Category 3J-only applications?
The borough must notify the Mayor initially, but the Mayor is not required to provide the ordinary initial response. Before refusing such an application, the borough must send the required refusal material and allow 21 days from the receipt date notified by the Mayor, unless released earlier. The Mayor may take over determination; the ordinary power to direct refusal does not apply to this category-only procedure. [2]
This distinction affects the programme and the documents needed at the point of a proposed refusal. It does not mean that every 50-home application is decided at City Hall. The relevant Order establishes a notification and intervention mechanism, not automatic transfer of every qualifying application. [2]
What does call-in mean?
Here, “call-in” means that the Mayor directs that the Mayor will act as the local planning authority for the application. It is different from an initial consultation response and from a direction telling the borough to refuse. The Order sets tests for exercising that power; it is not a developer's entitlement to a different decision-maker. [1]
The March housing package also announced broader Mayoral intervention concerning qualifying Green Belt and Metropolitan Open Land applications. The May 2026 legislation implements changes to the relevant category and includes transitional provisions. Check the actual route before assuming that an older application has moved into the new regime. [4][2]
What to put in the programme
Identify the referral route before fixing the decision programme. Record who will assemble the required material, the date of the Mayor's written receipt acknowledgement and whether an early release has been given. A borough committee resolution and completion of the relevant referral procedure are separate milestones. [1][2]