R (on the application of Halton Borough Council) (Respondent) v Secretary of State for Housing, Communities & Local Government (Appellant)

Case summary

Case ID

UKSC/2026/0025

Parties

Appellant(s)

Secretary of State for Housing, Communities & Local Government

Respondent(s)

Halton Borough Council

Issue

Does the ‘collapse’ of a party’s expert witness under cross-examination during a planning appeal demonstrate that the party must have behaved unreasonably such that a costs award may be made against them?

Facts

Halton Borough Council (“the Council”) approved the construction of 139 new dwellings on land in the town of Runcorn. The land is close to the Runcorn Chemical Complex, an industrial centre for the manufacture of chemicals. The Health and Safety Executive (“the HSE”) and Viridor, a company with a plant in the complex, objected to the proposal on safety grounds. The Council concluded that the development was safe on the basis of its own safety policy and expert advice from a firm of specialist management consultants. The Secretary of State for Housing Communities and Local Government (“the Secretary of State”) ‘called in’ the planning application and appointed a planning inspector to conduct an inquiry. The HSE and Viridor participated in the inquiry as interested parties. The Council relied on expert evidence from one of the consultants advising it. Under cross-examination, the Council’s expert witness accepted that its safety policy did not comply with the National Planning Practice Guidance. The expert conceded that if he were in the planning inspector’s position, he would strongly advise the Secretary of State to refuse the Runcorn development planning permission. As a result of this concession the Council withdrew its support for the development. The developer in turn withdrew its planning permission application. HSE and Viridor sought to recover the costs of participating in the inquiry from the Council. The Secretary of State, acting through a member of the Planning Inspectorate, decided the council had behaved unreasonably by supporting the planning application on the basis of expert evidence which failed to withstand cross-examination. The Secretary of State therefore ordered the Council to pay HSE and Viridor’s costs. The Council applied for judicial review of this decision. This claim failed before the High Court but succeeded before the Court of Appeal. The Secretary of State now appeals to the Supreme Court.

Date of issue

3 March 2026

Case origin

PTA

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