Ivor Harrison v Secretary of State for Levelling Up, Housing and Communities & Ors

On a challenge under section 288 of the Town and Country Planning Act 1990, a mistake of fact is unlawful where it concerns an existing, objectively verifiable and uncontested fact, was not caused by the claimant, and played a material, though not necessarily decisive, part in the decision-maker’s reasoning.

The court must assess materiality objectively in the context of the decision as a whole. A planning inspector must take account of relevant third-party representations, but need not rehearse every argument. Under section 66(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990, the desirability of preserving a listed building or its setting attracts considerable importance and weight. Regulation 5A of the 1990 Regulations imposes consultation duties at the application stage; on appeal, the Secretary of State has a discretion whether to consult.

The claimant challenged, under section 288 of the Town and Country Planning Act 1990, the Secretary of State’s decision allowing an appeal against refusal of outline planning permission for up to nine self-build dwellings at Caxton.

Ground 1 alleged that the inspector materially misstated that a flood risk assessment had been submitted and that the drainage officer was satisfied with it. Ground 2 alleged breach of the statutory duty concerning the setting of listed buildings and a failure to consult Historic England after the local planning authority had failed to do so.

The central issues were whether the factual mistake materially influenced the inspector’s reasoning, whether the inspector had taken account of flooding representations, and whether the statutory consultation regime imposed an appeal-stage duty to consult Historic England.

1. Outcome. Ground 1 succeeded. The Secretary of State’s decision allowing the planning appeal was quashed. Ground 2 failed.
2. Mistake of fact. The four requirements identified in E v Secretary of State for the Home Department were satisfied: there was a mistake about an existing fact; the fact was uncontentious and objectively verifiable; the claimant was not responsible; and the issue was whether the mistake played a material part in the inspector’s reasoning.
3. The mistake was material. The inspector incorrectly believed that the evidence included a flood risk assessment addressing whether the development would increase flood risk elsewhere, and that the drainage officer was satisfied with that information. His conclusion that he had no clear reason to disagree with the drainage officer was expressly based on the evidence before him, which he misunderstood. The error therefore affected the reasoning as a whole and was not merely the taking into account of an immaterial consideration.
4. The inspector did comply with the duty under article 33(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015 and regulations 13, 15 and 16 of the Town and Country Planning (Appeals) (Written Representations Procedure) (England) Regulations 2009. He identified the residents’ flooding representations, including the concern about increased risk to nearby properties, and engaged with them by considering the drainage officer’s response.
5. Heritage duty. The inspector’s brief consideration of Caxton Hall and the other heritage assets did not create substantial doubt about compliance with section 66(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990. He distinguished the factual reference to the curtilage of Caxton Hall from the evaluative question whether its setting would be preserved, and reached the planning judgment that the settings would be preserved. There was no need expressly to address flood risk as a heritage issue because it had not been advanced as affecting heritage significance.
6. Historic England. Regulation 5A of the Planning (Listed Buildings and Conservation Areas) Regulations 1990 imposed the relevant notice and consultation obligation on the authority determining the planning application. It did not impose an express duty on the Secretary of State when determining a section 78 appeal, and no such duty could be implied. At appeal stage the Secretary of State had a discretion whether to consult Historic England, reviewable on ordinary Wednesbury principles. No error in the exercise of that discretion was established.
7. The court declined to apply the statutory-effect principles in R (Black) v Secretary of State for Justice to imply a duty for a different purpose. The material mistake meant that it could not be said that the Secretary of State would necessarily have reached the same decision without it, so discretion did not save the decision.

First-instance judicial review under section 288 of the Town and Country Planning Act 1990. The court quashed the Secretary of State’s appeal decision on Ground 1 and rejected Ground 2.