A recent government consultation proposes that the new section 73B of the Town and Country Planning Act 1990 can provide a solution to the issues created by overlapping, incompatible planning permissions. 

Case law confirms that:

  • Where there are two overlapping permissions which are materially inconsistent, should the carrying out of Permission B make it physically impossible to carry out the rest of Permission A, then it is unlawful to carry out further development under Permission A (known as the Pilkington principle).
  • When considering whether development under Permission B would make it physically impossible to comply with Permission A, you have to consider the whole site of Permission A unless Permission A was granted on a severable basis (per the Supreme Court decision in Hillside).

This casts doubt on the ability to rely on “drop in” permissions with the intention of providing for alternate development in a small part of a large scheme that is already being implemented.

  • A permission will only be severable if this is expressly clear on the face of it. 
  • These principles apply to both outline and full permissions (per Dennis).

This leaves developers in a difficult position where there are overlapping permissions which were not granted on a severable basis. The Supreme Court in Hillside suggested that the route forward would be to apply for a new permission for the entire site. However, this comes with inherent difficulties (not least: increased planning application fees, the need to adapt to evolved planning policies for any new application and potential CIL implications). 

The government is consulting on the extent to which section 73B could help address these issues. S73B (which was introduced by the Levelling Up and Regeneration Act 2023 but is not yet in force) will facilitate changes to a permission (to the description of development and/or conditions) where the effect of the variation permission would not be “substantially different” from that of the existing permission.  The authority is limited to considering the merits of the variation under section 73B. The government sees this as a potential solution, on the basis that, in many cases, changes will not take the proposed development beyond the original masterplan and therefore are not “substantially different”. 

However, there is no definition or test for what is “substantially different” and it will be a matter of planning judgement. The government is unwilling to provide prescriptive guidance, but experience of section 73 applications would suggest that general guidance or examples as to the scope of permissible changes would be helpful.

The consultation does acknowledge that section 73B may not address all circumstances and the government is therefore seeking views on alternative options to manage the operation of overlapping permissions – for example via a new general development order which would deal with overlapping permissions in prescribed circumstances (such as for a specific class of development). 

For now, developers must take care when implementing overlapping and inconsistent permissions to avoid invalidating any future development under the original permission that may have taken years to obtain. The solution to addressing those matters must be considered carefully on a case-by-case basis.

The consultation closes on 1 May 2024.