Teresa Casey & Anor v Secretary of State for Housing, Communities and Local Government & Anor

In a statutory planning review, an inspector’s decision is unlawful where it proceeds on a material and objectively verifiable mistake about the location of proposed development in a flood-risk zone. The court must assess whether the error materially affected the planning balance; it need not uphold the decision merely because many other findings remain unaffected.

Where flood policy requires sequential testing before any exception test, the decision-maker retains judgment as to the precise methodology. However, the safety of occupiers must be properly assessed and weighed, particularly where the development is in a lower-risk zone but access passes through a higher-risk zone and alternative sites are given weight.

The claimants sought statutory review under section 288 of the Town and Country Planning Act 1990 of an inspector’s dismissal of their section 78 appeal. The appeal concerned planning permission for a Gipsy/Traveller site for six caravans at Greenacres, Crawley.

The claimants argued that the inspector had wrongly found that four touring caravans would be partly within Flood Zone 2, despite the statement of common ground recording that the caravans were on hard standings in Flood Zone 1. They also challenged the inspector’s treatment of flooding safety, the sequential test and the exception test.

1. Decision quashed. The inspector’s decision was quashed and the appeal was remitted for redetermination.
2. A claimant challenging planning judgment faces a high threshold. The court reviews legality, not the merits or the weight given to material considerations. The distinction between whether a matter is material and the weight it receives remains fundamental, as explained in Tesco Stores Ltd v SSE [1995] 1 WLR 759 and R (Newsmith Stainless Ltd) v SSETR [2017] P.T.S.R. 1126.
3. The inspector made a material mistake of fact. The statement of common ground clearly recorded that the caravans were outside Flood Zone 2. That was an uncontentious and objectively verifiable fact. The inspector neither rejected the statement nor explained why it was not accepted. The location of the caravans was material to the assessment of flood risk, and the decision proceeded on the basis that some caravans were partly in Flood Zone 2.
4. The error was fundamental to the evaluation of the planning balance. It was not possible to say that the outcome would inevitably have been the same without it. The court therefore applied the approach in Simplex GE (Holdings) Ltd v Secretary of State for the Environment [2017] PTSR 1041 and R (oao Weston Homes plc) v SSLUHC [2024] EWHC 2089 (Admin).
5. The second ground also succeeded to the extent that the inspector’s safety assessment was irrational. National policy required the sequential test before the exception test, but that did not remove the need to assess the safety of occupiers in detail. The inspector had given moderate weight to the absence of suitable alternative sites, yet failed adequately to assess matters including access through Flood Zone 2 and the safety of residents in a flood. The exception test did not necessarily have to be applied in full, but its safety aspect had to be properly assessed and placed in the balance.
6. The court’s conclusion was not that planning permission had to be granted, but that the appeal required lawful redetermination. Any consequential matters not agreed by the parties could be determined on written submissions.

The judgment does not state a further appellate history. It records that an earlier inspector’s decision dated 9 December 2022 had been quashed by the High Court and remitted for redetermination, but gives no citation for that decision.