By Andrew Morgan and Charlotte Coyle


Published 07 November 2022


In March 2021 we provided clarification on the incompatibility between multiple planning permissions, following the Court of Appeal’s decision in Hillside Parks Ltd v Snowdonia National Park Authority [2020] EWCA Civ 1440. The decision was appealed and the Supreme Court’s judgement was given on 2nd November.


This case concerns planning permission for 401 houses within the Snowdonia National Park based on a masterplan. That permission was not fully built out, and between the original grant of permission in 1967 and 2011, 16 permissions were granted for dwellings on the same site, each being built out in full – departing from the masterplan.

In 2017 the Local Planning Authority disputed that the original 1967 permission could still be fully implemented because the development carried out under the later permissions rendered the original masterplan scheme impossible to deliver. On the facts of Hillside the High Court and Court of Appeal came to the same conclusion – but clarifying that it could be possible for a later permission to be carried out without interfering with the work of another, but a “holistic” approach must be taken when interpreting permissions.

The Supreme Court’s Update

The Supreme Court has clarified the following key principles for amendments of what it called ‘multi-unit’ schemes:

  • if works under a second permission make works under the first permission physically impossible to carry out, then further development under the first permission will be unlawful if taken as a whole the departure from the original scheme is material;
  • a drop-in application may be achievable where a scheme can be severed into component parts so as to comply with the above test;
  • the materiality of the physical conflict caused by a departure from the original scheme and the severability of development will turn entirely on the facts of the particular consents

The Court also helpfully confirmed that where part of a development authorised by an earlier permission is unfinished it is not necessarily unlawful and open to enforcement – consistent with a subsequent permission being relied upon for delivery of the balance.

Our take

Drop-in applications can therefore achieve the means to amend a scheme provided they are carefully considered against the above principles, taking into account the wider ‘consent’ and its planning history – which is often complicated by variations of multiple planning permissions over years. The decision in Hillside is a cautionary tale on its own facts but the implications pose real risks for jeopardising valuable permissions if scheme amendments are not well conceived. DACB Planning can provide clear legal advice on your amendment proposals to mitigate these risks.