Trudie Elizabeth James, R (on the application of) v London Borough of Enfield

A planning permission may be challenged for mistake of fact where an objectively verifiable factual premise materially influenced the decision, even if it was not decisive. A daylight assessment using an area-weighted average must reflect the rooms and windows actually involved; treating separate spaces as one room can make the analysis materially erroneous. The Equality Act 2010 Public Sector Equality Duty requires substantive and rigorous consideration of potential equality impacts; a statement that the duty was considered is not enough. A permitted-development fall-back is relevant only where there is a realistic prospect of implementation. These issues were arguable, but the evidence did not justify interim relief.

The claimant, the immediate neighbour of a proposed residential extension, challenged the council’s grant of planning permission. She alleged that the daylight assessment wrongly treated her kitchen and two conservatories as one room, that the council failed to comply with the Public Sector Equality Duty concerning a disabled resident, and that it wrongly relied on permitted development rights as a fall-back. The hearing concerned permission to bring the judicial review and an application for an injunction and stay pending determination of the claim.

Disposition. The court found the judicial-review claim arguable on mistake of fact, failure to perform the Public Sector Equality Duty and reliance on permitted development rights. Interim injunctive relief and a stay were refused.

1. Mistake of fact. Applying the four requirements identified in E v Secretary of State for the Home Department [2004] EWCA Civ 49, the court held that the weighted-average daylight analysis proceeded on the objectively verifiable but false premise that the kitchen and two conservatories formed one room. The error was arguably material because the officer relied on the analysis. The claimant was not responsible for the mistake: the flyaround images were not intended to show internal walls, and only 72 hours were available to respond to the assessment. Under section 31(3C) of the Senior Courts Act 1981, the court could not say that the outcome would highly likely have been the same without the error.
2. Equality duty. The principles summarised in Quarry Mews Ltd v Secretary of State for Housing Communities and Local Government and Oxford City Council [2025] EWHC 1968 required substantive and rigorous consideration. Although Bolton Metropolitan Borough Council v Secretary of State for the Environment [2017] PTSR 1091 confirmed that every consideration need not be expressly addressed, a bare statement that the Public Sector Equality Duty had been considered did not demonstrate compliance. Failure to perform the duty was therefore arguable.
3. Fall-back position. Following South Buckinghamshire District Council v Secretary of State for the Environment, Transport and the Regions [1999] PCLR 72 and Snowden v Secretary of State for the Environment [1980] JPL 749, a fall-back development required a realistic prospect of implementation. Evidence of intention was not invariably necessary, but practicability and utility had to be apparent. That was not established on the material before the court.
4. Interim relief. Applying R (Medical Justice) v Secretary of State for the Home Department [2010] EWHC 1425 (Admin), there was a serious issue to be tried, but the balance of convenience opposed relief. The alleged health effects were unsupported by medical evidence. Any completed works could be removed if permission were quashed, and delay and the public interest attracted only limited weight.