Lisle-Mainwaring & Anor v Royal Borough of Kensington and Chelsea

A statutory challenge to a development plan document under Planning and Compulsory Purchase Act 2004, section 113, engages conventional public law principles. The court reviews legality, rationality and relevant considerations, but does not reconsider the planning merits.

Whether an alternative is a “reasonable alternative” for strategic environmental assessment is primarily an evaluative judgment for the planning authority, subject to ordinary public law review. An Inspector’s reasons need address the principal important controversial issues, but need not answer every submission point. A planning authority may adopt a restrictive policy where it has rationally identified and assessed competing environmental, social and economic objectives.

The claimants challenged the defendant local planning authority’s adoption of Policy CL7, the Basements Planning Policy, on 21 January 2015. The first claimant wished to construct a basement and the second claimant designed and constructed basements.

The claim alleged that the authority and the Inspector failed to consider permitted development rights, failed to assess a proposed case-by-case policy as a reasonable alternative under the environmental assessment regime, pursued a false objective of reducing excavation, breached the sustainable development duty, and gave inadequate reasons.

1. Statutory review. Section 113(3)(a) of the Planning and Compulsory Purchase Act 2004 has the same substantive scope as the corresponding provisions of the Town and Country Planning Act 1990. It permits review on conventional public law grounds, including irrationality and failure to take account of relevant considerations. The court’s function remains supervisory and does not extend to reviewing the merits of the planning policy.
2. Permitted development. The authority and Inspector had properly considered permitted development rights, including the risk that the new policy might encourage their greater use without planning controls over construction impacts. The authority had identified that problem in earlier consultation documents, contemplated an Article 4 direction, and included a monitoring mechanism. The weight to give the risk was a matter of planning judgment.
3. Policy objectives and sustainable development. Limiting the scale and cumulative impact of basement construction was a genuine and important policy objective, alongside achieving high standards of design and construction. The authority had assessed the policy against relevant environmental, economic and social objectives and had complied with section 39 of the 2004 Act.
4. Reasonable alternatives. The assessment of whether a proposed alternative is “reasonable” is an evaluative assessment for the local planning authority, reviewable on ordinary public law principles. An option which does not achieve the authority’s rationally identified objectives need not be assessed. The proposed case-by-case, uncapped approach was rationally rejected because it would not provide sufficient clarity or address the identified construction impacts.
5. Reasons and consultation. The Inspector’s reasons were intelligible and adequate under the principles in South Bucks District Council v Porter (No 2) [2004] UKHL 33. The authority had provided sufficient opportunity for representations on the policy objectives, and the later correction to the sustainability appraisal was legitimate.
6. The application was dismissed.