Hillside Parks Limited v Snowdonia National Park Authority [2022] UKSC

This Supreme Court decision concerned a 1967 planning permission for the development of 401 houses (based on a master plan showing the layout of the houses and roads) in an area known as ‘Balkan Hill’ in Aberdyfi. The planning authority is Snowdonia National Park Authority.

In what the judgment referred to as “glacial” progress, only 41 houses have been built at the site since 1967 and these were developed under a series of additional planning permissions. The Supreme Court had to decide whether the developer of the site was entitled to carry out further development at the site pursuant to the 1967 permission or whether the development carried out in accordance with other permissions meant the developer could no longer rely on the 1967 permission.

Some key takeaways:

• The Supreme Court held the developer could no longer develop the site pursuant to the original 1967 permission. The dwellings built to date meant it was now physically impossible to develop the site in accordance with the original permission. The Supreme Court noted that the test of physical impossibility applies to the whole site covered by the unimplemented planning permission, not just the part of the site on which a landowner now wishes to build.

• The Supreme Court noted that “where a planning permission is granted for the development of a site, such as a housing estate, comprising multiple units, it is a question of interpretation whether the permission authorises a number of independent acts of development, each of which is separately permitted by it, or whether it is to be construed as a permission for a single scheme which cannot be disaggregated in this way”.

• In relation to an argument that later permissions were variations of the original development scheme, the Court’s view was that where there is a full planning permission for one entire scheme and a developer wishes to depart from it in a material way, a fresh planning permission will be required. The Court noted that this is a consequence of the very limited powers that a local planning authority currently has to make changes to an existing planning permission. The judgment also highlights that the Levelling Up and Regeneration Bill proposes giving the local planning authority power to grant a planning permission that varies an existing permission but only if the local planning authority is satisfied that "its effect will not be substantially different from that of the existing permission”.

• In relation to a development, a failure or inability to complete a project for which planning permission has been granted does not make development carried out pursuant to the permission unlawful. However, the Supreme Court noted that (in the absence of clear express provision making it severable) a planning permission is not to be construed as authorising further development if at any stage compliance with the permission becomes physically impossible. Any other interpretation would lead to practical difficulties, uncertainty and unfairness, for example from those who had already purchased completed units.

• Despite the developer’s arguments to the contrary there is no principle in law that a planning permission can be abandoned. Planning permission runs with the land and affects third parties. Introducing a doctrine of abandonment, which is not provided for in the legislation, would be inconsistent with the requirement of public accessibility.

Hillside Parks Limited v Snowdonia National Park Authority [2022] UKSC 30.