Background
Persimmon Homes Severn Valley applied for outline planning permission for 190 homes at Rectory Farm (North), Chescombe Road, Yatton — a site in Flood Zone 3a situated approximately 5 km from the coast. North Somerset District Council failed to determine the application, prompting Persimmon to appeal to the Secretary of State. A planning inspector (David Prentis BA BPI MRTPI) held a ten-day public inquiry and, by decision letter dated 18 March 2025, allowed the appeal and granted outline permission. The inspector found that the NPPF flood risk sequential test was not passed — twelve sequentially preferable sites existed — but treated that failure as a matter of substantial weight in the planning balance rather than an automatic bar, ultimately concluding that the benefits outweighed the harm and granting permission under paragraph 11(d) of the NPPF. The inspector also found that the proposed dwellings could be made safe for their lifetime, accepting the developer’s defended-scenario flood modelling (using the Higher Central Climate Change Allowance) rather than the Council’s preferred undefended scenario.
North Somerset District Council challenged the decision by statutory review under section 288 of the Town and Country Planning Act 1990. Permission to proceed was granted by Johnson J on 2 October 2025. The case was heard by Mrs Justice Jefford on 27 January 2026 and judgment handed down on 12 June 2026. The review raised two grounds: (1) the inspector misunderstood or misapplied NPPF policy by proceeding to the exception test notwithstanding failure of the sequential test, when local and national policy would not rule out development on sequentially preferable sites; and (2) the inspector’s conclusion that the development could be made safe for its lifetime was irrational or inadequately reasoned.
Central to the dispute was the interaction between NPPF paragraphs 173–179 (the sequential test and exception test for flood risk) and paragraph 11(d) (the presumption in favour of sustainable development). The Council relied on Planning Practice Guidance stating that the exception test is not a tool to justify development in flood risk areas where the sequential test reveals other reasonably available lower-risk sites, unless relevant local and national policies would provide a clear reason for refusing development in those alternative locations. Persimmon relied on the Court of Appeal’s and Holgate J’s reasoning in the Lynchmead Farm (Mead) litigation, which confirmed that failure of the sequential test is not automatically fatal and may be given reduced weight in the overall planning balance where substantial unmet housing need exists.
The Court’s Holding
Mrs Justice Jefford considered both grounds of review against the established legal framework: that the interpretation of planning policy is a matter of law for the court, but the application of policy and the weight to be given to material considerations are matters of planning judgment for the inspector alone; that decision letters must be read flexibly, with a presumption that a specialist planning inspector understood the policy framework correctly; and that a reasons challenge succeeds only where the party aggrieved is substantially prejudiced by a failure to give intelligible and adequate reasons. The court approached Ground 1 by asking whether, reading the decision letter as a whole, the inspector must have misunderstood NPPF flood risk policy, and considered the significance of the PPG’s guidance that the exception test is only appropriate where policies would provide a clear reason for refusing development at alternative locations.
On Ground 2, the court examined whether the inspector’s acceptance of the defended flood scenario (rather than the undefended scenario) as the design event, and his reliance on a 600 mm freeboard to address uncertainty about higher climate change allowances, were rational and adequately explained. The inspector had noted the Environment Agency’s agreement with the developer’s modelling approach, the EA’s confirmation at the inquiry that it did not allege the proposed houses would themselves be at risk under that scenario, and the agreement of all expert witnesses that freeboard is an appropriate planning tool for managing uncertainty.
The opinion text as provided is truncated immediately before the court’s final dispositive conclusions; however, the judgment sets out the full legal framework and the competing arguments with precision, and the court’s analysis of the inspector’s reasoning on both flood safety and the sequential/exception test interface is directed squarely at whether the inspector’s approach was legally permissible in light of Mead and the PPG.
Key Takeaways
- Failure of the NPPF flood risk sequential test does not automatically preclude planning permission; under the Mead line of authority, it is a weighty factor in the planning balance, and substantial unmet housing need may reduce the weight attached to that failure.
- The exception test in NPPF paragraphs 177–179 is only properly engaged where relevant local and national policies would provide a clear reason for refusing development at sequentially preferable alternative sites — the PPG precludes its use simply to bypass a failed sequential test.
- A planning inspector’s choice of flood design event (defended versus undefended scenario) and climate change allowance is a matter of expert planning judgment; courts will defer to that judgment where the inspector has engaged with the evidence and given rational, intelligible reasons, particularly where the Environment Agency has agreed with the adopted approach.
- Decision letters must be read as a whole and charitably, not parsed as statutory text; the burden lies on the claimant to demonstrate the inspector must have misunderstood policy, not on the inspector to demonstrate affirmatively that he understood it.
Why It Matters
This case sits at the intersection of two of the most contested areas of English planning law: the chronic shortage of housing land and the escalating risks of tidal flooding from climate change. The Secretary of State’s decision to allow 190 homes on a site that failed the sequential test — on the basis that housing need and a weak five-year land supply outweighed flood risk concerns — tests the outer limits of the flexibility recognised in Mead and raises fundamental questions about the weight planners can place on flood risk policy when housing delivery pressures are acute. The court’s examination of whether the PPG’s caveat on the exception test constitutes a binding interpretive limit or merely a weighting consideration is of direct relevance to planning authorities and developers across flood-risk areas of England.
The case also has practical significance for how flood risk assessments are constructed. The dispute over defended versus undefended modelling scenarios, and the role of freeboard in managing upper-end climate change uncertainty, will affect how future applications in coastal and estuary flood zones are designed and challenged. The Environment Agency’s written agreement with the developer’s modelling approach — and the weight the inspector gave to it — highlights the importance of early engagement with the EA in setting the parameters of any site-specific flood risk assessment.