By Andrew Morgan and Charlotte Coyle


Published 23 January 2024


In March 2023 London Borough of Southwark granted a s96A application that inserted the word "severable" into the description of development of an outline planning permission granted in 2015 for the phased redevelopment and regeneration of the Aylesbury Estate in South East London. A resident of Aylesbury Estate lodged a judicial review. The question Holgate J in the High Court considered was whether the insertion of "severable" was material or not – the answer fell on whether or not the outline permission was already severable. The resident argued that the amendment was "material" and outside the scope of s96A, the Council and Notting Hill Genesis argued that the outline permission was phased and already severable, and the amendment was made to confirm the position explicitly.

A "drop-in" detailed application had been submitted for Phase 2B of the regeneration of Aylesbury Estate. The Council and Notting Hill Genesis sought to use the s96A amendment to ensure that in implementing that drop-in permission, the outline permission would remain in tact and could be relied on without falling foul of any Hillside and Pilkington arguments.

A brief recap: Hillside and Pilkington

By way of quick re-cap, Hillside upheld Pilkington. In 2022 the Supreme Court decided that where a planning permission is granted for a development such as a housing estate, comprising multiple units, it is a question of construction whether "the permission authorises a number of independent acts of development, each of which is separately permitted by it" or whether it is to be construed as a permission for a single scheme which cannot be disaggregated in that way. It said that where a permission is granted for multiple units, it is unlikely to be the correct interpretation that it is severable (and so the physical impossibility test in Pilkington will apply). The Court in Hillside said that save for some "clear contrary indication" as to severability, the developer cannot combine building part of a proposed development with building something different from and inconsistent with the approved scheme on another part of the site. The Supreme Court went on to say that this should not be taken too far, and departures from the (original) permitted scheme were allowed where they were not material in the context of the scheme as a whole. Hillside concerned a detailed permission that was granted in the 1960s. It was distinguishable from many of the outline large scale, phased permissions currently being built out. Thus far, developers and local planning authorities have been construing phasing as evidence of severability.


The 2015 outline permission was very clearly and obviously phased. It encompassed a range of parameter plans and Statements/Strategies that must be complied with. The drop-in application did not comply with those documents. Holgate J said that a detailed permission for phasing is compatible with a single planning permission. "The mere inclusion of phasing provisions in a detailed permission would be insufficient to amount to a "clear contrary indication" that the consent is severed into discrete planning permissions. The same is true of an outline permission". He went on to conclude that in order to disapply Pilkington, freestanding permissions must be identified. The conclusion was that the insertion of the term "severable" was material, and the s96A decision was ultra vires. It was agreed between the parties in this case that if the permission was severable, the judicial review would have failed.


The three key take aways are:

  • S96A is limited in scope, it can only be used to make non-material amendments. It does not result in the grant of a new planning permission. Although the LPA has a discretion as to what is material, this decision clearly demonstrates that objectors to schemes do look closely at amendments and do find ways to thwart attempts to re-plan sites – even if the lack of mandatory consultation on s96A applications keeps them under the public radar.
  • Retrofitting planning permissions to avoid potential Hillside issues is going to be difficult. Drop in applications can achieve amendments to a scheme however you can no longer simply rely on a drop in for a single phase or sub-phase to avoid any Hillside risk.
  • Where drop in applications are a material departure from the planning permission and would (if implemented) create physical impossibility, a Hillside risk will arise.

The proposed s73B to be introduced by the LURA will provide a third option for varying planning permissions. It will allow for changes, provided they are not "substantially different" from the existing permission and it will not result in a new (and alternative) permission. Unlike s73, s73B will allow for amendments to the description of development.

DACB can advise you on the best tool to amend your permission.