London Borough of Lambeth v Secretary of State for Levelling Up, Housing and Communities [2024] EWHC 1391 (Admin)

Lambeth flat amalgamation is an important Planning Court judgment on whether joining two flats to make one larger home amounts to a material change of use requiring planning permission.

The court upheld an Inspector who had granted a lawful development certificate for the proposed amalgamation. The loss of one dwelling was a planning consequence, but on the evidence before the Inspector it was not a consequence of sufficient significance to make the change material.

Neutral citation

[2024] EWHC 1391 (Admin)

Court

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

Judgment date

10th June 2024

Judge

Mrs Justice Lang DBE

Case number

AC-2023-LON-003350

What the Lambeth flat amalgamation case decided

The proposal was to combine Flats 26 and 27 at Peninsula Heights, Albert Embankment, into one four-bedroom home by removing an internal wall. Lambeth refused both planning permission and a certificate of lawfulness.

On appeal, the Inspector allowed both appeals. He found that the two flats were separate planning units, but that combining them would not create a significant change in the character of the residential use. He also found that the loss of one housing unit was not, in the circumstances then before him, a planning consequence of significance.

Lambeth challenged that decision under section 288 of the Town and Country Planning Act 1990. Mrs Justice Lang dismissed the challenge on all six grounds.

Joining two flats does not automatically amount to development

Section 55 of the 1990 Act makes the subdivision of one dwelling into two or more dwellinghouses a material change of use. It does not contain an equivalent rule saying that the reverse process, joining dwellings together, is always development.

The question therefore remains whether the particular amalgamation produces a material change in the character of the use. That is a question of fact and degree for the decision-maker.

The court endorsed the approach in R (Royal Borough of Kensington and Chelsea) v Secretary of State for Communities and Local Government [2016] EWHC 1785 (Admin): the loss of an existing use can have planning consequences even without an amenity impact, but the decision-maker must assess whether those consequences are significant enough to make the change material.

Housing policy is relevant, but it is not the whole answer

Lambeth argued that its housing policies should determine whether the amalgamation was development. The court rejected that approach.

A development plan policy which addresses the loss of housing is relevant to the section 55 assessment, but it is not automatically decisive. Section 55 does not say that a development plan policy determines whether a material change of use has occurred.

The Inspector was therefore entitled to look at the actual planning consequence of losing one dwelling in the context of Lambeth’s housing delivery. He found that amalgamations represented a very small proportion of housing delivery and had not materially affected the borough’s ability to boost supply.

The London Plan did not prohibit amalgamations

The court also agreed with the Inspector’s interpretation of the London Plan and Lambeth Local Plan.

The relevant policies sought to increase and safeguard housing, but they did not contain an express prohibition on amalgamating flats. Supporting text referred to amalgamations and their effect on housing totals, but supporting text is not itself development plan policy.

Policy H8 required lost housing to be replaced by housing at existing or higher densities with at least equivalent floorspace. On the facts of this proposal, the Inspector was entitled to conclude that the policy did not prevent the amalgamation.

The Inspector could decide both appeals

The applicant had appealed both the refusal of the lawful development certificate and the refusal of planning permission on a without-prejudice basis.

Once the Inspector decided that the amalgamation was not development, the planning permission appeal became academic. Even so, the court held that he was entitled to decide it in the alternative in case his certificate decision was later overturned.

Previous appeal decisions must normally be brought to the Inspector’s attention

Lambeth also relied in court on three other appeal decisions concerning flat amalgamations. They had not been put before the Inspector in this appeal.

The court confirmed the general rule that an Inspector is not expected to search for every potentially relevant appeal decision. If a party knows of a relevant decision, it should draw it to the Inspectorate’s attention. Exceptional cases can arise where consistency requires the Secretary of State to know about a closely related decision, but this was not one of them.

What this means if you want to combine two homes

The case does not create a blanket permitted route for joining flats or houses. The answer still depends on the character of the existing and proposed use, the planning consequences of losing a dwelling, the development plan and the evidence at the time.

Our guide to combining two houses or flats explains the practical planning position. Where you want certainty before carrying out the works, see our page on a certificate of lawfulness of proposed use or development.

Read the full Lambeth judgment

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

Lambeth Flat Amalgamation Case Law Page Updated: 9th September 2026