UK Planning – New year, same planning challenges

On 17 January the High Court handed down the latest decision in a long and increasingly knotty line of authorities concerned with the compatibility of planning permissions, scheme changes and, in particular, the widely used practice of drop-in permissions. The decision in Dennis is significant and, unfortunately, unhelpful for developers formulating strategies for major schemes or those with existing developments involving drop-in permissions. Read on for a review of the key principles and implications.

What’s the background?

In March 2023 LB Southwark granted a non-material amendment under section 96A of the 1990 Act to insert the word “severable” into the description of development of an outline permission for the phased redevelopment and regeneration of the Aylesbury Estate.

The position of the council and the developer was that the outline permission was severable in any event and that the amendment made under section 96A was only intended to make that express on the face of the permission.

Treating the outline permission as severable would allow the developer to implement a drop-in permission to replace an existing phase of development with a new (otherwise incompatible) form of development. In this case, the developer sought to deliver an uplift in housing provision that could not otherwise be accommodated within the parameters of the outline permission.

The claimant, a long-standing local resident and seasoned campaigner against the redevelopment of the Aylesbury Estate, argued that:

  • on the true construction the outline permission was not severable; and

  • the amendment to make it severable could not be treated as non-material (its purpose and effect was to make the outline permission more flexible, disapplying the established principle in Pilkington).

The essential question for the Court was the scope of the rights conferred by the outline planning permission, and whether those were changed materially by the section 96A amendment.

The answer to that question turned on whether the outline permission was itself a “severed or severable consent” – a concept thrust to prominence following the landmark Hillside decision of the Supreme Court at the end of 2022.

Whilst Hillside didn’t consider the practice of drop-in permissions, great store had been set by many practitioners on the analysis that if a development was phased, it was likely to be severable.

That was the line of reasoning advanced in the present case by the council and developer, who submitted that the outline permission was severable on the basis of its phases.

What did we learn?

Simply put – Mr Justice Holgate concluded that being phased doesn’t, of itself, mean that a permission is severable. Any decision to grant a severed planning permission must be expressed unequivocally. 

At this point, the decision introduces the problematic concept of a planning permission being “severed into discrete planning permissions”, the precise meaning of which is not immediately clear and is at risk of being held hostage to very different – and potentially unhelpful – interpretations.

On the facts of the case, the outline permission was found to be a single, indivisible planning permission – not a severed permission or a collection of freestanding permissions.

The phasing provided for by the outline permission involved spatially discrete phases which the permission required to be delivered sequentially. The approved design and access statement and design code ran as a thread throughout the permission. All of this was found to be compatible with the grant of a single permission and inconsistent with the grant of a severed permission. 

Taking a peek behind the permission itself, the High Court found there to be no indication in the officer’s report to committee or the environmental statement connected with the outline permission that individual phases might subsequently be replaced by a materially different drop-in application.

The High Court had no doubt that on a true construction the outline permission was not severable before the section 96A amendment. It was a single planning permission with provisions for phasing.

Holgate J also expressed his strong reservations about the legality of an amendment to a planning permission which simply inserts uncertain, bare language such as “severable” into a description of development without any other indication of the way in which the permission is to be considered severable. Despite the council and the developer arguing that the phasing of the outline permission resulted in its severability, the introduction of the word “severable” wasn’t limited in that way.

To the extent that the amendment did sever the outline permission, the effect of that was to disapply the Pilkington principle and made it unnecessary to apply the physical impossibility test to a future material departure from the development authorised by the outline permission.  On that basis, it significantly enlarged the “bundle of rights” conferred by the permission, and was a material amendment of the outline permission that went beyond the scope of the powers in section 96A. The claim was allowed and the purported non-material amendment to the outline permission quashed.

What are the implications?

The decision in Dennis gives rise to some significant – and challenging – implications for those involved in significant regeneration and redevelopment schemes.

Good planning involves coherent, integrated proposals that work as a whole. Long-term development projects evolve and change over time, and this requires a certain level of flexibility. There creates an inherent tension which makes achieving severability at the outset tricky, although not insurmountable.

The High Court said a lot about the factors that pointed away from severability – but did not make any concrete suggestions as to how severability of a planning permission should be achieved.

Developers formulating strategies for major schemes will need to consider carefully how permissions can be future-proofed. Permissions need to be made unequivocally severable. This could be achieved, for example, by building in mechanisms to ensure that, where drop-in development is introduced, safeguards are in place to secure compatibility with the underlying consent. Even so, the treatment of site-wide plans or controlling documents poses real challenges.

Those with existing developments involving drop-in permissions will need to ensure the compatibility of their consenting strategy with the findings of the High Court in Dennis.

One of the key challenges faced by developers when considering drop-in permissions has been the reluctance of planning authorities to engage with the approach given the perceived risks and uncertainty brought about by the recent case law. The decision in Dennis is unlikely to give reluctant authorities the confidence to embrace the drop-in solution.  The proposal of the Supreme Court in Hillside that developers should simply secure a fresh planning permission for the entire site surely isn’t the answer.

Although permission to appeal was refused by the Judge on the papers, the council may now apply to the Court of Appeal for permission to appeal the decision. We’ll keep you up to speed with developments. Your usual Hogan Lovells contact is available to discuss the implications of the Dennis decision in the meantime.


R (Aysen Dennis) v LB Southwark and Notting Hill Genesis [2024] EWHC 57 (Admin) (17 January 2024)



Authored by David Wood.

Hannah Quarterman
David Wood
Senior Associate
Robert Gowing
Senior Associate


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