R (on the application of Aysen Dennis) v London Borough of Southwark [2024] EWHC 57 (Admin)

Dennis v Southwark is an important Planning Court case on section 96A of the Town and Country Planning Act 1990. It considered whether Southwark could use a non-material amendment to add the word severable to a large phased outline planning permission for the Aylesbury Estate.

Mr Justice Holgate held that it could not. On its proper interpretation the outline permission had originally been a single, integrated permission. Adding severability materially enlarged the bundle of planning rights because it sought to avoid the effect of the Pilkington principle after a later, incompatible drop-in permission.

Neutral citation

[2024] EWHC 57 (Admin)

Court

High Court of Justice, King's Bench Division, Planning Court

Judgment date

17th January 2024

Judge

Mr Justice Holgate

Case number

AC-2023-LON-001410

The Aylesbury Estate outline permission

Southwark granted an outline planning permission in August 2015 for the phased redevelopment of much of the Aylesbury Estate. The permission covered a large mixed-use scheme with up to 2,745 homes, community and employment uses, public realm, roads, landscaping and other infrastructure.

The consent incorporated parameter plans, a Design and Access Statement and a Design Code Strategy. Those documents tied together matters such as development parcels, movement routes, open space and the sequence of later phases.

A later drop-in scheme created the severability issue

By 2022 the development plan had changed and Notting Hill Genesis wanted phase 2B to provide more housing than could be accommodated within the parameters of the 2015 outline permission.

Rather than seek reserved matters approval under the outline consent, the developer applied for a separate detailed planning permission for phase 2B. That type of freestanding application is often described as a drop-in permission.

The concern was whether carrying out the new phase 2B permission would make it physically impossible to continue relying on the earlier outline permission for later phases.

The Pilkington and Hillside problem

The issue arose from the principle in Pilkington v Secretary of State for the Environment and the Supreme Court’s later decision in Hillside Parks Ltd v Snowdonia National Park Authority.

In broad terms, if development carried out under one planning permission makes it physically impossible to carry out development authorised by another permission, the second permission may no longer be capable of further implementation.

Hillside also made clear that a multi-unit permission is not normally treated as a collection of separate permissions unless there is a clear contrary indication.

Southwark used section 96A to add the word severable

Before issuing the separate phase 2B permission, Southwark approved an application under section 96A to alter the description of the 2015 outline permission so that it referred to a severable phased development.

Southwark and the developer argued that this did not change the substance of the consent. Their case was that the permission had already been severable by phase and that the amendment merely made that position express.

Section 96A can alter the operative part, but only non-materially

The court confirmed an important distinction between section 96A and section 73.

Section 73 is concerned with conditions and cannot be used to rewrite the description of development granted by an existing permission. Section 96A is wider in one respect: it can make a change to the planning permission itself, including its operative part.

But the statutory limit is critical. The change must still be non-material.

Phasing did not make the outline permission inherently severable

Southwark and Notting Hill Genesis relied heavily on the fact that the scheme was an outline permission to be delivered in phases over many years.

Mr Justice Holgate rejected the suggestion that phasing itself creates severability. A phased detailed permission or a phased outline permission can still be a single planning permission.

The court said that where severability is intended, the decision should be expressed unequivocally. A mere phasing arrangement is not enough to amount to the clear contrary indication referred to in Hillside.

The original permission was a single integrated consent

Looking at the 2015 permission as a whole, the court found no clear indication that it had been granted as separate permissions for the individual phases.

The incorporated documents linked the phases together. They included site-wide parameter plans, an ordered phasing sequence, movement routes, public space and design controls which were intended to work across the redevelopment as a whole.

Mr Justice Holgate concluded that the permission was a single planning permission with provisions for phasing, not a set of freestanding consents.

Adding severability materially enlarged the planning rights

Because the original permission was not severable, adding that concept after the event changed the legal effect of the consent.

The amendment sought to enable later phases to continue under the outline permission even if a materially incompatible phase 2B was built under another permission. In other words, it sought to remove or reduce the risk that the Pilkington principle would prevent further reliance on the original consent.

The court held that this significantly enlarged the bundle of rights granted by the outline permission. That was a material change and therefore outside the power in section 96A.

The section 96A decision was quashed.

The word severable was also too uncertain

The court did not need this point to decide the case, but Mr Justice Holgate also expressed strong reservations about simply inserting the bare word severable into a large planning permission.

It did not say whether the permission was severed by phase, plot, building or some other unit. For a large development there could be many possible forms of severance.

That is a useful drafting warning. If a planning authority intends a permission to be severed, the extent and effect of that severance should be made clear rather than left to a single undefined label.

What Dennis does not decide

The court was not deciding whether the later phase 2B development would in fact trigger the Pilkington principle and prevent implementation of the remaining phases. That question had not yet arisen on the ground.

The case instead concerns the interpretation of the original permission and the lawfulness of trying to change its legal character through section 96A.

It also does not mean every phased permission is indivisible. Severability remains a matter of construction. The important point is that it should be supported by clear wording and by the structure of the permission itself.

Read the full Dennis judgment

The approved Planning Court judgment is held in the Planning Geek case law library. Gold Members can open the protected PDF below.

Related Planning Geek guidance

See our guide to non-material amendments under section 96A, our explanation of section 73 applications and our guide to outline planning permission.

Dennis Case Law Page Updated: 9th September 2026