The Supreme Court has confirmed in Hillside Parks Ltd v Snowdonia National Park Authority [2022] UKSC 30; [2022] PLSCS 177 that while developers are entitled to choose which multi-unit planning permission they implement, they cannot mix and match discrete elements of different permissions. While the case concerned a planning permission granted more than 50 years ago, the decision will have far-reaching consequences for the building industry.
In 1967, the respondent authority granted planning permission for a large housing estate of 401 dwellings near Aberdyfi in the Snowdonia National Park. The approved plan identified the proposed location of each house and the road system for the estate. Since the 1967 permission was granted, only 41 houses have been built, none in accordance with the approved plan.
In proceedings in 1987, a declaration was granted that development under the 1967 permission could still be lawfully completed in accordance with the approved plan “at any time in the future”. Subsequently, various planning permissions were granted for parts of the site and those developments undertaken, which also departed from the approved plan. Since 2004, houses were built on areas inconsistent with the approved plan without any planning permission.
In 2017, the authority informed Hillside, the current owner and developer of the site, that it could not now implement the 1967 permission since it was not physically possible to build the development in accordance with the approved plan. Hillside sought declarations that the 1967 permission remained valid and could be carried out to completion as declared in 1987. The claim was dismissed by the High Court and an appeal to the Court of Appeal failed.
The Supreme Court has now unanimously dismissed Hillside’s appeal. Two inconsistent permissions can be granted for development of land and a developer can choose which to implement. Where development has taken place under one permission, whether another permission may lawfully be implemented depends upon whether it remains physically possible to carry out the development authorised by the second permission in light of what has already been done under the first: Pilkington v Secretary of State for the Environment [1973] 1 WLR 1527. In 1987, the court had decided that it remained possible to implement the 1967 permission despite the development which had by then taken place, but that left open the effect of the development which had taken place subsequently.
The Supreme Court rejected the appellant’s argument that it had not abandoned plans for development under the 1967 permission: there is no room for any principle of abandonment in planning law. Planning permission for a multi-unit development is granted for that development as an integrated whole in the absence of clear express wording making it severable. The development on part of the site under the post-1987 permissions, which departed from the 1967 permission and was inconsistent with the approved plan, had made it physically impossible – and so unlawful – to carry out any further development under the 1967 permission. The analysis of a planning permission is one of substance, not form. In substance the post-1987 permissions were departures from, not variations of, the 1967 permission irrespective of their label.
Louise Clark is a property law consultant and mediator
