High Court rules London Borough of Southwark's planning permission amendment beyond authority, emphasizing clarity on severability in Aylesbury Estate redevelopment.

Citation: [2024] EWHC 57 (Admin)
Judgment on


In the case of Aysen Dennis, R (on the application of) v London Borough of Southwark, the High Court of Justice examined a judicial review regarding a planning permission amendment under section 96A of the Town and Country Planning Act 1990 (TCPA 1990). The claimant, Aysen Dennis, contested that the amendment made by the London Borough of Southwark to an outline planning permission (OPP) for the redevelopment of the Aylesbury Estate was material and thus beyond the scope of section 96A. The central question was whether the amendment, which introduced the term “severable” into the OPP, was material in nature and if the decision to grant such an amendment should be quashed.

Key Facts

The contested amendment aimed to make the OPP “severable,” implicitly suggesting phases of the development could independently proceed or be modified without affecting the validity of the overall permission. The claimant argued that the amendment was material as it altered the bundle of rights conferred by the original OPP, invoking the “Pilkington principle” from the case Pilkington v Secretary of State for the Environment [1973] which addresses the implications when one planning permission physically obstructs another on the same land.

Contrarily, the defendant, London Borough of Southwark, and the interested party, Notting Hill Genesis (NHG), posited that the OPP inherently implied severability in relation to its phases and that the amendment made under section 96A merely sought to clarify this position. The court’s task was to discern the true construction of the OPP and the implications of the amendment.

A series of precedents and principles were central to the case analysis:

  1. Severability: Severability in planning permissions can refer to the ability to treat parts of a planning permission as independent or discrete permissions. The amendment’s lawfulness hinged on whether the original OPP already implicitly allowed severability amongst its different development phases.

  2. The Pilkington Principle: Stemming from Pilkington v Secretary of State for the Environment [1973] and recently discussed in Hillside Parks Limited v Snowdonia National Park Authority [2022], this principle entails that once a portion of a site is developed under one permission, it may render another permission on the same site non-reliant if the developments conflict physically, thereby cancelling the latter permission unless that permission is construed as severable.

  3. Material and Non-material Amendments (Section 96A of TCPA 1990): The distinction between material and non-material amendments is pivotal under section 96A. Material changes require a new planning permission, whereas non-material amendments can be made to existing permissions without new applications.

  4. The Finney Principle: Referencing Finney v Welsh Ministers [2020], the ruling delineates that section 73 of the TCPA 1990 only permits changes to conditions of a permission, not the fundamental description of the development it authorizes.

  5. Construction of Planning Permissions: The court emphasized well-established principles that permissions should be read as a whole, considering both the operative part and conditions collectively, against the backdrop of the relevant statutory framework and the permission’s intended scope.


Mr. Justice Holgate, concluding that the OPP should not be interpreted as inherently severable based on its phasing or the nature of the development allowed, held that the insertion of the word “severable” constituted a material amendment to the bundle of rights within the OPP. Moreover, the term “severable” lacked clarity to indicate the extent of severance. Consequently, the court ruled that the s.96A decision was ultra vires, rendering the amendment outside the bounds of the authority provided by the TCPA 1990.


The High Court’s decision highlights the delicate balance between the lawful flexibilities accorded to phased developments under planning permissions and the statutory limitations on amending those permissions. Severability in planning permissions cannot be presumed and must be explicitly and unambiguously conveyed, lest it materially alter the rights conferred by the original grant. The ruling reinforces the sacrosanct nature of the “Pilkington principle,” affirming its engagement across both detailed and outline permissions unless clear contra-indications suggest otherwise. The outcome of this case shall prompt planners and developers to scrupulously evaluate the terms and potential amendments of planning permissions and underscores the implication of precise language in such legislative exercises.

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