Halton Borough Council, R (on the application of) v The Secretary of State for Housing, Communities and Local Government

In a called-in planning inquiry, an authority’s withdrawal of support after its expert made a damaging concession in cross-examination is not, without more, unreasonable conduct justifying a costs order. The costs decision-maker must identify the procedural requirement allegedly breached and the point or event at which reliance on the expert became unreasonable. There is no general procedural requirement to test an apparently competent expert’s evidence against cross-examination or to second-guess it routinely. A difference of expert opinion, or evidence being undermined in cross-examination, is insufficient by itself. Unreasonableness requires a trigger, such as an obvious flaw or knowledge, or reason to know, that the expert’s views were untenable. Failure to reconcile findings of material change and no material change is a demonstrable flaw in reasoning.

A developer applied to Halton Borough Council for planning permission for housing near the Runcorn Chemicals Complex. The Council initially resolved to grant permission despite objections from the Health and Safety Executive. The Secretary of State called in the application. During a closed part of the inquiry, the Council’s public safety expert accepted that, if acting as inspector, he would advise strongly against permission. The Council withdrew its support, and the developer withdrew the application.

The Secretary of State awarded partial costs to the Health and Safety Executive and Viridor Energy Limited, finding the withdrawal unreasonable. The Council’s judicial review challenge was dismissed by Fordham J: [2024] EWHC 2030 (Admin); [2024] Costs LR 1709. The appeal concerned whether the reasoning was irrational and whether adequate reasons had been given. The central issue was whether the Council’s reliance on its expert until cross-examination, and its subsequent withdrawal, amounted to unreasonable procedural conduct.

Lewison LJ gave the judgment of the court. Asplin LJ and Coulson LJ agreed. The appeal was allowed.

1. The Secretary of State’s broad power to award costs arose under section 250(4) of the Local Government Act 1972, as applied to called-in applications by section 322 of the Town and Country Planning Act 1990. The published Guidance distinguished substantive conduct before call-in from procedural conduct during the inquiry. In a called-in case, withdrawal without good reason could justify costs.
2. The Guidance was not law, but a decision-maker departing from it had to give reasons. On judicial review, the court could intervene for material misdirection or public-law irrationality. Reasons had to explain the decision and resolve the principal controversial issues without creating substantial doubt about legality: R (Finch) v Surrey CC [2024] UKSC 20; South Bucks DC v Porter [2004] UKHL 33.
3. The Secretary of State correctly rejected the contention that the Council’s original resolution to grant permission was itself unreasonable. The critical issue was therefore whether the Council had withdrawn support too late.
4. The expert’s answers in cross-examination were new evidence and were sufficiently material to cause the Council to withdraw. The Secretary of State nevertheless concluded that there had been no material change in the evidence. That conclusion was irreconcilable with his finding that the Council had changed position because of the expert’s evidence. He also failed to identify when or why reliance on the evidence became unreasonable. This was a leap in reasoning and a demonstrable flaw.
5. There was no suggestion that the Council had breached a specific rule or inspector’s direction, that its expert evidence lacked a respectable evidential basis, or that the expert’s views were obviously untenable. A party is not generally required to test its own expert’s evidence to see whether it will withstand cross-examination. A difference of expert opinion is insufficient. A trigger causing doubt about reliability is required, although the position may differ where an obvious flaw exists or the party knew or should have known that the expert’s views were untenable.
6. The Council had held conferences with counsel and its experts before and after exchange of evidence. Discussion and preparation were permissible, subject to avoiding witness coaching. The crucial concession concerned the validity of local policy rather than public safety, so it could not reasonably have been anticipated that the issue would arise in cross-examination of the public safety expert.
7. The reasoning applied equally to the costs awards in favour of the Health and Safety Executive and Viridor. The appeal was allowed.

• Court of Appeal (Civil Division): allowed the Council’s appeal against the costs decisions, [2025] EWCA Civ 1566.
• High Court of Justice, King’s Bench Division, Planning Court: Fordham J dismissed the Council’s judicial review challenge to the Secretary of State’s costs decisions, [2024] EWHC 2030 (Admin); [2024] Costs LR 1709.