London Borough of Islington, R (on the application of) v Mayor of London & Anor

A planning decision-maker may lawfully conclude that a scheme provides the maximum reasonable amount of affordable housing through an overall viability judgment. Reasonable disagreement about valuation inputs does not establish legal error and does not require an express rebuttal of every competing valuation. The decision-maker need not show that its conclusion was the only reasonable judgment available. For Aarhus costs protection, the relevant question under CPR 45.41(2) is whether the decision challenged is wholly or partly subject to the Aarhus Convention, rather than the precise grounds advanced. A planning decision concerning housing may therefore qualify even where the challenge turns on valuation.

Two borough councils sought judicial review of the Mayor of London’s decision to grant planning permission for a mixed-use development at the Mount Pleasant Sorting Office site. The Mayor had exercised his statutory power to determine the application and had approved a section 106 agreement.

The renewed application for permission focused on two issues: whether the Mayor had lawfully assessed the maximum reasonable amount of affordable housing, particularly by reference to competing site valuations; and whether the section 106 agreement secured the required linkage between different parts of the development. The court also determined whether the claim was an Aarhus Convention claim for costs purposes.

1. Permission refused. The claimants’ grounds were not arguable.
2. The relevant planning policies required the maximum reasonable amount of affordable housing, having regard to the individual circumstances of the site, viability, subsidy and phased development. The Mayor’s officers and consultants had asked the correct questions and reached a rational planning judgment. The report read fairly and in context did not show that the decision-maker had substituted a merely reasonable outcome for the maximum reasonable amount.
3. Conflicting valuation evidence did not itself establish an error of law. Planning judgments commonly involve disagreement about valuation inputs. The decision-maker was entitled to prefer one reasonable valuation methodology over another and was not required to provide an explicit rebuttal of every competing figure. The conclusion did not have to be the only reasonable conclusion available.
4. The section 106 agreement secured the required linkage between the two parts of the site by preventing commencement of the Phoenix Place scheme until a binding contract existed for the enabling works. The agreement therefore fell within the scope of the delegated authority.
5. For costs purposes, CPR 45.41(2) directs attention to the decision, act or omission challenged, not to the particular grounds of challenge. The planning permission was at least partly subject to the Aarhus Convention because it concerned housing and included extensive environmental matters. The claim was consequently an Aarhus Convention claim and the costs orders were to proceed on that basis.

The judgment concerned a renewed application for permission to apply for judicial review after Lewis J had refused permission on paper on 25 June 2015. Ouseley J refused permission after oral renewal.