Guildford Borough Council v Secretary of State for Levelling Up Housing and Communities & Anor

Where a local planning policy defines the original building for Green Belt extensions or alterations by reference to the building as it existed on 1 July 1948, or the first building originally built after that date, that building is the baseline for assessing proportionality. The decision-maker must account for the cumulative effect of later extensions and additions. The replacement-building exception is analytically distinct and cannot be used to treat a replacement dwelling as the baseline for a later extension application. Although applying policy to an unforeseen factual situation may involve planning judgment, that does not permit the decision-maker to depart from the policy’s wording without identifying a genuine gap. A failure to apply the correct baseline is an error of law.

The claimant local planning authority sought a statutory review under section 288 of the Town and Country Planning Act 1990 of an inspector’s decision granting planning permission for extensions and alterations to Foxwell Cottage, a dwelling in the Green Belt.

The original dwelling had been demolished and replaced under planning permissions granted in 2003. The inspector treated the existing replacement dwelling and garage as the baseline for assessing whether the proposed works would result in disproportionate additions. Permission to challenge was granted on the issue whether that approach misinterpreted policy P2 of the Guildford Local Plan.

1. Claim allowed. The inspector’s decision was quashed and the planning appeal was remitted for redetermination.
2. Policy P2 implemented the National Planning Policy Framework exception for extensions or alterations which do not result in disproportionate additions over and above the size of the original building. P2 defined the original building as either the building existing on 1 July 1948 or, if no building then existed, the first building originally built after that date.
3. The natural meaning of P2 required the original building, as originally built, to be used as the baseline. The wording was directed to preventing cumulative extensions and additions which might be modest individually but disproportionate in aggregate. The fact that the original building had been demolished did not displace that requirement.
4. The extension or alteration exception and the replacement-building exception addressed different applications. The inspector had impermissibly elided P2(2)(a) and P2(2)(b) by treating the replacement dwelling as the baseline for the extension proposal.
5. The potential practical difficulties identified by the Secretary of State, including reconstructing the size of a demolished building, did not justify departing from the wording of P2. Nor had the inspector identified a policy gap or explained that he was exercising planning judgment to fill one.
6. The court distinguished interpretation of policy, which was a matter for judicial analysis, from planning judgment in applying policy. On a fair reading of the decision letter, the inspector had misunderstood the policy rather than merely made an evaluative planning judgment.

First-instance statutory review. The court quashed the inspector’s planning decision and directed that the appeal be resubmitted for redetermination.