High Court clarifies interpretation of section 55 and GPDO prior approvals in enforcement appeal

In Amin Dharmeshkumar v Secretary of State for Housing, Communities and Local Government & Anor [2025] EWHC 25123 (Admin), the High Court dismissed a challenge to an enforcement notice concerning unauthorised residential conversion works, providing important clarification on the interpretation of section 55 of the Town and Country Planning Act 1990 and the resolution of ambiguities in GPDO prior approvals.

The appellant converted a three-storey former office building to twelve flats, relying on a 2017 planning permission for external works and a Class O prior approval for change of use. The local authority served an enforcement notice alleging breach of planning control, which the appellant contested on grounds that the works were lawful.

The section 55(2) exclusion

The central issue concerned whether extensive rebuilding works—including removal of external facades, roof replacement, window changes, staircase alterations, and internal reconfiguration—constituted "development" requiring planning permission, or fell within the section 55(2)(a) exclusion for works of "maintenance, improvement or other alteration" which do not materially affect external appearance.

Deputy High Court Judge Tim Smith rejected the appellant's argument that the inspector had misunderstood the relationship between sections 55(1), (1A), and (2). Reading the decision letter benignly, the inspector had correctly identified that whilst works fitting the description in section 55(2)(a) must be assessed, the two-stage test requires both that works constitute maintenance/improvement/alteration and that they either affect only the interior or do not materially affect external appearance.

Following Hillside Parks v Snowdonia National Park Authority [2022] UKSC 30, only the unauthorised elements—fenestration changes and lift shaft overrun—required assessment, since other works were covered by the 2017 permission. The court found the inspector entitled to conclude these works materially affected external appearance, particularly the fenestration changes. Relying on Haringey LBC v Secretary of State [2020] P & CR 13, the court confirmed that section 336's definition of "building" includes "part of a building", meaning materiality could be assessed by reference to the affected part rather than the whole structure.

Prior approval ambiguities

The second ground challenged the inspector's resolution of an admitted error in the prior approval decision notice, which referenced two non-existent plans alongside two existing ones. The appellant argued this created no enforceable requirement to comply with application plans, since the prior approval lacked express incorporation wording such as "in accordance with".

The court distinguished between planning permissions and GPDO prior approvals. Whilst case law from R v Ashford BC, ex parte Shepway DC [1999] PLCR 12 establishes that planning permissions require express incorporation language, paragraph W(12)(a) of Schedule 2 to the GPDO imposes a statutory requirement that development be carried out "in accordance with the details approved". This statutory code itself incorporates the approved details, making the specific wording on the decision notice less critical.

Where ambiguity exists—as with the phantom plan references—recourse to extrinsic material from the application is permissible. The inspector was therefore entitled to consider all application drawings to resolve the ambiguity and conclude the development departed from approved details.

The court noted no injustice resulted, since the appellant had previously assumed the application plans were binding and had unsuccessfully sought variations through paragraph W(12).

Both the substantive and costs appeals were dismissed, leaving undisturbed a partial costs award favouring the appellant for the council's unreasonable refusal to engage with variation requests.