R (Manby) v Hackney: planning permission quashed over failure to apply the 45-degree rule

The Planning Court has quashed Hackney's grant of planning permission for a rear and roof extension, holding that the council's officers referred to the 45-degree rule as a material consideration but never actually applied it to the neighbouring property that had objected.

In R (Manby) v London Borough of Hackney [2026] EWHC 1543 (Admin), HHJ Russen KC, sitting as a High Court judge, found the decision unlawful on grounds of failure to take account of a material consideration, process irrationality, breach of the Tameside duty and inadequate reasons.

Background

The claimant, Bronwen Manby, lives at 89 Culford Road, next door to a property whose owner obtained delegated permission in August 2025 for lower and upper ground floor rear extensions and a mansard roof. Her objection expressly raised the 45-degree rule, a design guide in the council's 2009 Residential Extensions and Alterations Supplementary Planning Document intended to prevent undue loss of daylight, overshadowing and loss of outlook to neighbours.

Policy LP17 of the Hackney Local Plan directs that extension schemes "should have regard to" the SPD, and paragraph 3.14 states that all extensions should comply with the rule. The design and access statement accompanying the application addressed compliance in relation to the property on the other side, number 85, but did not expressly address number 89.

The officer's evidence

The officer's report noted the objection, quoted the SPD verbatim and concluded the scheme was acceptable in amenity terms. After the claim was issued, the case officer, Ms Hadadi, provided a witness statement clarifying that she had treated the rule as a flexible guide, had not determined whether it was met, had not relied on the DAS assertion of compliance and had conducted no site visit or calculation. She could not now recall whether she believed the rule was satisfied.

That evidence shifted the challenge onto whether proceeding without any determination of compliance meant the decision failed to take account of a material consideration.

The decision

HHJ Russen KC accepted that the SPD, not being part of the development plan, created no presumption against permission, and that its application called for planning judgement. But he held that having regard to a material consideration required more than lip service. Merely noting the rule without assessing how much weight it carried, or how it bore on the decision, was not a proper exercise of planning judgement. To take the rule into account, the report would have needed to establish the centre point of the nearest habitable room window at number 89, which was never done.

The judge distinguished R (Gill) v Brent [2021] EWHC 67 (Admin), where the guidance was imprecise and could be assumed to have been applied. Here the evidence rebutted any such assumption. He also declined to treat the report as written by one officer for a knowledgeable second decision-maker, since both had signed it and the reasons were jointly theirs. This was therefore not a Hughes v Kirklees [2026] EWCA Civ 308 situation calling for caution before inferring a gap in reasoning.

The same oversight established process irrationality, a breach of the duty in Secretary of State for Education and Science v Tameside MBC [1977] AC 1014, and inadequate reasons, since the residential amenity conclusion appeared to have been reached regardless of the rule.

On remedy, the judge held the high threshold in section 31(2A) of the Senior Courts Act 1981 was not met. He declined to accept the officer's characterisation of the breach shown on the claimant's undisputed drawing as "minor", declining to enter the "forbidden territory" of exercising his own planning judgement. The decision was quashed.