Unseen Changes: The Quiet Power of S106 Variations

The planning system in London rightly places a high priority on strategic oversight, especially when it comes to major development and affordable housing. The Mayor of London plays a central role in this process through the powers granted under the Town and Country Planning (Mayor of London) Order 2008, which ensures that applications of potential strategic importance (PSI) are assessed against regional priorities.

However, a procedural gap exists that merits closer attention: the treatment of Deeds of Variation (DoVs) to Section 106 agreements after planning permission has been granted.

A DoV is not, in legal terms, a planning application. As such, it does not fall within the scope of the Mayor’s statutory referral powers under the 2008 Order unless it accompanies a new or amended planning application, such as one made under Section 73. This means that significant changes to obligations, such as the removal of a late stage viability review or a shift in affordable housing tenure, can be made without formal referral to the Mayor, even if the original scheme was referable.

This position is clear in law, but it has led to differing interpretations in practice. Some boroughs take a cautious approach, consulting the GLA informally when strategic obligations are proposed for change. Others take the view that where no formal mechanism requires GLA involvement, none is necessary. The result is inconsistency and uncertainty.

The Mayor has attempted to provide policy guidance through the 2017 Affordable Housing and Viability SPG, which encourages consultation when affordable housing provisions are materially changed. However, this guidance is non-binding, and there is no legal obligation on local planning authorities (LPAs) to notify or involve the GLA when processing a DoV in isolation.

This situation poses a dilemma.

On one hand, LPAs should be empowered to manage post-permission negotiations, especially where outcomes such as increased affordable housing or earlier delivery are being secured. On the other hand, the absence of a formal referral mechanism for DoVs may reduce transparency and undermine the strategic oversight the GLA is intended to provide, particularly where the changes result in reduced policy compliance.

It’s also worth recognising that not all changes are equal. The removal of a late-stage review in exchange for a higher up-front affordable housing offer may be seen as a reasonable trade-off. But reductions in affordable housing, particularly late in the day and without public scrutiny, are more difficult to justify, especially where schemes were only approved on the basis of initial viability constraints.

In short, this is an area of planning regulation that would benefit from clearer expectations and guidance, if not formal legislative reform. As development economics shift and more schemes seek to vary post-permission agreements, consistency in approach becomes essential. Whether through updated GLA procedures or national policy clarification, the goal should be a system that supports flexibility while maintaining public confidence in the strategic planning framework.

Writer: Matt Hill, Planning Director