Sequential test, exception test and the planning balance: lessons from the Yatton judgment

What the High Court decided

The court dismissed North Somerset Council's statutory challenge under section 288 of the Town and Country Planning Act 1990. The council had sought to overturn an inspector's decision granting outline permission for 190 homes at Yatton on a Flood Zone 3a site. Mrs Justice Jefford found no error of law. The inspector was entitled to weigh the substance of the exception test as material considerations after the sequential test had failed, and his conclusion that the homes would be safe was neither irrational nor inadequately reasoned. The council's central argument, she held, sought to draw "a distinction without a difference".

How a failed sequential test still led to permission at Yatton

The case arose from Persimmon's appeal for 190 homes at Rectory Farm (North), Chescombe Road, Yatton, a site in Flood Zone 3a around 5km from the coast. Inspector David Prentis found the sequential test was failed because twelve sequentially preferable sites were reasonably available, and he gave that failure significant weight alongside the residual flood risk. The full appeal background is covered in our analysis of what the Yatton appeal means for planning.

He did not stop there. Faced with a substantial local housing shortfall, he concluded the scheme's benefits, market and affordable housing in particular, outweighed the flood risk, and granted permission under the tilted balance at paragraph 11(d) of the National Planning Policy Framework. Flood risk, he found, did not amount to a strong reason to refuse, so footnote 7 did not switch off the presumption in favour of sustainable development. That is the decision the council took to court.

Sequential test versus exception test: why the difference mattered

The sequential test and the exception test do different jobs, as our explainer on the sequential and exception tests sets out in full. The sequential test steers development to land at the lowest flood risk: under NPPF paragraph 173, development should not be permitted where there are reasonably available sites at lower risk. The exception test, at paragraphs 177 to 179, only follows where the sequential test cannot be passed but the development may still be justified. It has two limbs that must both be met: wider sustainability benefits that outweigh the flood risk, and safety for the development's lifetime without increasing flood risk elsewhere.

North Somerset's case rested on a clean reading of that sequence. Once the sequential test is failed, the argument ran, the decision-maker never reaches the exception test, so applying it, or its content, is contrary to policy. The council accepted (following *Mead*) that the inspector should still weigh the failure in the planning balance, but argued he had instead applied the exception test by the back door to justify the development.

"A distinction without a difference": the exception test in the planning balance

The court rejected that argument. The inspector nowhere said he was applying the exception test. What he did was take the factors that make up its limbs into account as material considerations, which he was fully entitled to do under section 38(6) of the Planning and Compulsory Purchase Act 2004. Starting from the presumption that a specialist inspector understands policy, Mrs Justice Jefford found the natural reading of the decision was exactly that.

She also pinned down the flaw at the heart of the council's case. Neither the NPPF nor the Planning Practice Guidance says that, once the exception test is not reached, the matters within it must be ignored. If they did, "patently material considerations as to sustainability and safety would be excluded", leaving almost nothing in the balance and turning a failed sequential test into an automatic bar. That, the judgment confirms, is not how flood risk policy works.

The ruling builds on two recent decisions. *Mead*, upheld by the Court of Appeal, established that a failed sequential test is not automatically fatal, and we cover it in our guide to applying the sequential test post-Mead. *Gladman* quashed a refusal where an inspector had treated the absence of a sequential test as the end of the matter without a lawful balance, analysed in what the Gladman judgment means for the sequential test. As Mrs Justice Jefford put it, the argument that the inspector weighed "the product of the exception test" rather than the underlying material considerations "seeks to draw a distinction without a difference".

Was the development safe for its lifetime?

The council's second ground argued the scheme could not rationally be called safe, because an undefended scenario allowing for sea level rise would flood the houses by more than a metre. The court disagreed. The inspector had set the design event as the 1-in-200-year defended scenario with the Higher Central climate change allowance. That gave a design flood level of 6.28m AOD, with the site raised to 6.43m and finished floor levels at 6.88m, leaving 600mm of freeboard. The choice of design event was a planning judgment, and not an irrational one.

The undefended scenario was a sensitivity check, the "worst worst case", used to test the realistic design event rather than to define it. Treating the most extreme conceivable flood as the design event, the court noted, would make every coastal and riverside scheme undeliverable. Residual risk was managed through a Flood Management Plan secured by condition. On reasons, the decision was "clear and reasoned"; the council "may wish he had said even more, but that is not a basis for challenge".

What it means for planning practice

The practical lessons for anyone arguing flood risk at inquiry are concrete:

• A failed sequential test is a significant factor, not an automatic veto. It carries weight in the balance; it does not end the decision.
• Fight it on weight, not as a knockout blow. The real safeguard lies in the weight given to the failure, supported by evidence on housing need and the scale of any shortfall against preferable sites.
• The exception test's content stays material. Lifetime safety and wider sustainability benefits can be weighed even where the test is never formally engaged.
• Get the design event right. The realistic defended scenario plus freeboard is the benchmark; the extreme undefended case is a sensitivity check, not the standard a scheme must survive.
• Evidence carries the day. A robust flood risk assessment, a credible drainage strategy and deliverable planning conditions are what make the balance defensible.

It is worth being clear what the case is not. The High Court reviews the legality of a decision, not its planning merits. As Mrs Justice Jefford stressed, the court is not there to decide whether the balance was right or wrong, only whether it was lawful. The wider debate over whether the sequential test is being weakened in practice continues, a concern we examined in our piece on the TCPA's alarm over the sequential test.

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