Hillside Parks Ltd v Snowdonia National Park Authority

Planning permission is construed holistically. A permission for an integrated development ordinarily must be implemented fully in accordance with its terms. Later operations authorised by other permissions may make the original permission physically incapable of completion; further development under the original permission then requires fresh permission. A prior declaration that permission could be completed in future does not bind the parties regardless of later changes in fact or law. The Henderson/abuse of process doctrine requires a broad merits-based assessment, including public and private interests and material subsequent developments. The exceptional Lucas approach may apply where a permission authorises independent acts, but it did not apply to an integrated estate scheme.

Hillside Parks claimed declarations concerning a 1967 planning permission for a housing development. In 1987, Drake J declared that the permission had been implemented and could lawfully be completed at any time. After further development under additional permissions, Snowdonia National Park Authority contended that the original Master Plan had become physically impossible to complete.

The High Court dismissed the claim, holding that the 1987 declaration did not prevent consideration of later events and that the original permission could no longer lawfully be completed. The appeal concerned res judicata and abuse of process, the construction of the additional permissions, the Lucas exception, and the effect of post-1987 development.

1. The appeal was dismissed. Singh LJ gave the leading judgment, with David Richards LJ and Nicola Davies LJ agreeing.
2. A declaration that a planning permission could be completed at any time was not perpetual. Properly understood, the 1987 declaration addressed implementation and the possibility of completion on the facts and law then existing. It did not determine that completion would remain possible despite later factual or legal changes. The issue before the High Court concerned developments since 1987 and therefore was not subject to issue estoppel.
3. The general principles of res judicata apply in public law, subject to the principle that a statutory body cannot fetter its freedom to perform statutory duties or exercise statutory powers: Thrasyvoulou v Secretary of State for the Environment [1990] 2 AC 273. The Henderson/abuse of process doctrine is not absolute. It requires a broad, merits-based assessment of all the circumstances, including public and private interests. The significant legal developments since 1987, including Sage v Secretary of State for the Environment [2003] UKHL 22; [2003] 1 WLR 983, and the public interest in preventing inappropriate development in a National Park meant that the Authority was not barred from advancing its case.
4. Planning permission must generally be construed holistically. Development must be carried out fully in accordance with the final permission. The approach in Singh v Secretary of State for Communities and Local Government and Another [2010] EWHC 1621 (Admin) was endorsed. The later roads and housing were incompatible with the Master Plan, so the original permission could no longer be implemented and further development required a fresh permission. The Court expressly left open whether development already carried out under an earlier permission becomes unlawful merely because later operations are inconsistent with it.
5. The Lucas exception did not apply. Lucas was a highly exceptional, fact-specific decision in which the permission authorised independent acts of development. That construction may occasionally be available, but it is unlikely for a modern integrated housing-estate permission. The Court declined to overrule Lucas because it could not be satisfied, without the original permission, that it had been wrongly decided on its facts.

• Court of Appeal (Civil Division): In [2020] EWCA Civ 1440, the appeal was dismissed.
• High Court of Justice, Queen’s Bench Division: In [2019] EWHC 2587 (QB), HHJ Keyser QC dismissed the claim and held that later development had made completion of the 1967 permission physically impossible.