Peter Barclay & Anor v Secretary of State for Transport & Anor

Planning policy is interpreted as a practical whole, in its policy and factual context. It is not construed as a statute or contract. The court distinguishes that legal task from the decision-maker’s evaluative judgment when applying policy to particular facts.

An environmental finding that greenhouse-gas effects are moderately adverse does not contradict a conclusion that a project will not materially impair the Government’s ability to meet carbon targets. The two assessments answer different questions of degree. The adequacy of an environmental impact assessment, including whether non-CO₂ aviation emissions require quantification, is ordinarily an evaluative judgment reviewable only on irrationality grounds.

The Secretary of State made a development consent order authorising dual-runway operations and associated development at Gatwick Airport under the Planning Act 2008.

Peter Barclay and Communities against Gatwick Noise Emissions brought judicial-review claims. Mould J granted permission on limited grounds but dismissed both claims: [2026] EWHC 1556 (Admin).

The claimants sought permission to appeal. Their challenges concerned the interpretation of the Airports National Policy Statement, economic benefits, greenhouse-gas emissions, the Jet Zero Strategy, non-CO₂ emissions, and wastewater controls in the order. The central issue was whether any proposed ground had a real prospect of success or another compelling reason to be heard.

1. Both applications for permission to appeal were dismissed. Every ground was unarguable, had no real prospect of success, and disclosed no other compelling reason for an appeal.

2. The Airports National Policy Statement and the accompanying policy on making best use of existing runways had to be read as practical policy documents, as a whole and in their wider context. Their interpretation was a legal question, distinct from evaluative judgments in applying them. Properly construed, the policy supported capacity increases through more intensive use of existing runways beyond Heathrow, including Gatwick, provided that environmental concerns were addressed and the need was additional to or different from that met by Heathrow’s north-west runway.

3. The Secretary of State’s assessment that the project’s greenhouse-gas emissions had a moderate significant adverse effect under IEMA guidance did not contradict her conclusion under the policy that they would not materially affect the Government’s ability to meet carbon-reduction targets. The respective standards involved different questions and judgments of degree.

4. The adequacy and scope of environmental impact assessment were matters for the Secretary of State’s evaluative judgment, subject to irrationality review. She lawfully accepted a qualitative assessment of non-CO₂ aviation emissions where methodological uncertainty remained, while treating those emissions as an additional adverse warming effect. The precautionary principle did not require a different conclusion.

5. The Secretary of State was entitled to give full weight to the Jet Zero Strategy despite uncertainty in future technologies and emissions forecasts. Its monitoring, review and adjustment mechanisms, read with the statutory carbon-budget regime, supported that judgment. A later departmental monitoring return did not make it irrational to rely on the strategy or require consideration of an ongoing series of such returns.

6. The wastewater requirement was lawful. It was rational to assume that the statutory undertaker, environmental regulator and airport operator would act rationally if alternative treatment works became necessary. The provision allowing Thames Water Utilities Ltd to agree otherwise did not permit an uncontrolled departure from the order; it remained confined by the wastewater purpose and the order’s environmental-effects safeguard.

Pursuant to paragraph 61 of the Practice Direction (Citation of Authorities), the court certified that the decision may be cited as authority.

• Court of Appeal (Civil Division): refused both applications for permission to appeal and dismissed them: [2026] EWCA Civ 1040 .

• High Court, King’s Bench Division, Planning Court: Mould J granted permission on limited grounds, rejected those grounds, and dismissed both judicial-review claims: [2026] EWHC 1556 (Admin) .