Keep Chiswell Green v Secretary of State for Housing, Communities and Local Government & Ors

A party’s failure to identify a consideration arising after a planning inquiry has closed does not create an absolute procedural bar to a statutory review. The decision-maker may still act unlawfully by overlooking a matter which is so obviously material that disregarding it is irrational.

The test is Wednesbury irrationality. It is insufficient that the material could realistically affect the outcome; it must be a gamechanger. Its relationship and importance to the actual decision are central. A knowledgeable party’s failure to raise it is a powerful, though not conclusive, indication that it was not mandatory.

Material prepared for an emerging local plan will not necessarily be mandatory when the decision concerns particular planning applications and the decision-maker has a detailed, site-specific assessment of the relevant harm and benefits.

The Secretary of State allowed two planning appeals and granted outline permission for residential developments of up to 391 and 330 dwellings on green-belt sites near St Albans. An inspector found substantial green-belt harm but concluded that the housing and other benefits constituted very special circumstances.

After the inquiry closed, the Council published the Arup Green Belt Review as evidence for an emerging local plan. It reached conclusions different from an earlier review considered at the inquiry. No party supplied the new review to the inspector or Secretary of State or asked that it be considered.

Lang J dismissed the community group’s statutory review in [2024] EWHC 273 (Admin). She found a preliminary procedural bar and, alternatively, held that the Arup Review was not a mandatory material consideration. The appeal concerned whether the procedural bar existed and whether the review was so obviously material that the Secretary of State was legally bound to consider it.

1. Appeal dismissed. The judge erred in treating the appellant’s failure to raise the Arup Review as a preliminary procedural bar. Nevertheless, the review was not so obviously material that the Secretary of State acted irrationally by deciding the planning appeals without considering it.

2. Material arising only after an inquiry has closed must be distinguished from evidence or argument available during the inquiry. The latter should ordinarily be presented as part of a party’s case. For post-inquiry material, however, there is no absolute rule precluding statutory review merely because no party brought it to the decision-maker’s attention. The omission may instead bear on materiality, knowledge, irrationality and the court’s remedial discretion.

3. The statutory question under sections 70(2) and 79(4) of the Town and Country Planning Act 1990 is whether the consideration was so obviously material that failing to consider it was irrational. The test is not whether the material was realistically capable of changing the result. It must be a gamechanger. Relevant matters include the nature of the decision, the material’s importance to that decision and whether informed participants considered it significant enough to raise.

4. Rule 17 of the Town and Country Planning (Inquiries Procedure) (England) Rules 2000 gives the Secretary of State discretion to disregard or consider post-inquiry material. Notification and reopening are required under rule 17(5) only where new evidence disposes the Secretary of State to disagree with the inspector’s recommendation. The judge therefore erred in assuming that success on the claim would necessarily require the inquiry to be reopened.

5. The Arup Review addressed possible green-belt release through an emerging local-plan process. It did not decide whether very special circumstances justified the particular developments, and its recommendations had neither been incorporated into a plan nor independently examined. The inspector had undertaken his own detailed, site-specific assessment, attributed substantial weight to green-belt harm and balanced that harm against the developments’ benefits. The earlier SKM review served at most as a check upon that assessment.

6. The failure of both the Council, which commissioned the Arup Review, and the appellant to identify it as material reinforced the conclusion that it was not a mandatory consideration. Lewis LJ gave the judgment, with which Elisabeth Laing and Andrews LJJ agreed.

1. Court of Appeal (Civil Division): The appeal was dismissed in [2025] EWCA Civ 958. The court rejected the High Court’s preliminary procedural-bar analysis but upheld its alternative conclusion that the Arup Review was not a mandatory material consideration.
2. High Court, Planning Court: Lang J dismissed the statutory-review claim in [2024] EWHC 273 (Admin). She held that the claimant was procedurally barred from relying on material not placed before the decision-maker and, alternatively, that the Secretary of State had acted rationally by not considering the Arup Review.