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

The Court of Appeal dismissed the appellant's challenge to the Secretary of State's decision to allow two appeals for housing development in the Metropolitan Green Belt. The appeal contested (i) the judge's view that the claimant could not rely on material not placed before the inspector or the Secretary of State and (ii) whether a green belt review published after the inquiry (the Arup Review) was a mandatory material consideration the Secretary of State had to take into account. The court held that there is no absolute procedural bar to bringing a statutory review based on material arising after an inquiry closed, but that whether such material must be considered is governed by the public law irrationality test. Applying that test, the Arup Review—an early-stage evidence document prepared for plan-making—was not "so obviously material" that it was irrational for the Secretary of State not to take it into account. The Secretary of State had accepted the inspector's site-specific assessment of harm to the green belt and concluded that the benefits (principally housing) amounted to very special circumstances; the Arup Review did not demonstrate it would have been irrational to reach that decision.

Background and parties:

• The appeals concerned two outline planning applications for residential development within the Metropolitan Green Belt at Chiswell Green (Appeal A: up to 391 dwellings promoted by Cala Homes; Appeal B: up to 330 discounted affordable homes promoted by Headlands Way Ltd). St Albans City and District Council refused both applications. Keep Chiswell Green, a local community group, opposed the grant of permission and participated in the inquiry.

Procedural posture:

• An inquiry before an inspector ran from 17 April to 9 May 2023. The inspector recommended allowing both appeals. Before the Secretary of State decided, the Council published a new green belt evidence document (the Arup Review) on 16 June 2023 as part of its emerging local plan process; that document was not put before the inspector during the inquiry and was not supplied to the Secretary of State by any party prior to decision.
• The Secretary of State accepted the inspector's recommendations and granted planning permission on 22 March 2024. Keep Chiswell Green sought a statutory review under section 288 of the Town and Country Planning Act 1990, principally contending that the Secretary of State had unlawfully failed to have regard to the Arup Review.
• The High Court (Lang J) dismissed the claim on two bases: (a) procedural bar—parties must ordinarily place material before the inspector/decision-maker and the court should not entertain new evidence or grounds not relied on at the inquiry; and (b) on the merits, the Arup Review was not a mandatory material consideration and the Secretary of State had not acted irrationally in not taking it into account. The claimant appealed.

Issues before the Court of Appeal:

1. Whether the High Court was right to treat the absence of the Arup Review from the inquiry as a preliminary procedural bar to the statutory review claim.
2. Whether the Arup Review was "so obviously material" that it was irrational for the Secretary of State not to have regard to it when determining the appeals.

Court's reasoning and conclusion:

• The court clarified the applicable public law approach. Decision‑makers must take into account considerations that are "so obviously material" only as a matter of rationality (Wednesbury) and there is no absolute rule preventing a court from considering material arising after an inquiry closed. Case law (including The Bath Society and Cumberlege) demonstrates circumstances in which post‑inquiry material may be so obviously material that failure to have regard to it is unlawful. At the same time, decisions such as West and Mead govern the position where relevant material was available during the inquiry but not put forward.
• The Court of Appeal held that Lang J was wrong to treat the absence of the Arup Review as an absolute preliminary procedural bar; the correct approach is to consider whether the new material was so obviously material that it would be irrational not to take it into account. The judge should not decline to consider the statutory review claim solely on that procedural basis.
• Applying the public law test, however, the court concluded that the Arup Review was not "so obviously material" to the Secretary of State's decision. The Arup Review was an early‑stage evidential document prepared for plan‑making; it recommended no release of the sub‑areas containing the appeal sites but had not been accepted, incorporated in a draft plan or tested at examination. The inspector had made a detailed, site‑specific assessment of green belt harm, weighed that harm against the benefits (principal among them housing supply) and concluded that very special circumstances existed. The Arup Review addressed strategic plan allocations rather than the specific question of whether those particular developments individually secured very special circumstances. In those circumstances it was not irrational for the Secretary of State to proceed on the basis of the inspector's site‑specific findings and recommendations.

Appeal dismissed. The Court of Appeal held (i) there is no absolute procedural bar to bringing a statutory review based on material arising after an inquiry closed, so the High Court was wrong to refuse the claim on that sole basis; and (ii) on the merits the Arup Green Belt Review was not so obviously material that it was irrational for the Secretary of State not to take it into account before allowing the appeals: the Arup Review was an early-stage plan-making evidence document, was not determinative of the site‑specific planning balance, and the Secretary of State lawfully relied on the inspector’s detailed site-specific assessment and conclusions that very special circumstances outweighed green belt harm.

This is an appeal from the High Court (King’s Bench Division, Planning Court) decision of Lang J dismissing a statutory review claim [2024] EWHC 273 (Admin). Permission to bring the statutory review in the High Court had been granted by Eyre J (permission reference not otherwise stated in the judgment).