Uncategorized | March 16, 2021


A recent decision of the Court of Appeal in the case of Hillside Parks Ltd v Snowdonia National Park Authority [2020] EWCA Civ 1440 (“Hillside”) has raised eyebrows in the development industry over potential implications for multi-phased development schemes involving overlapping planning permissions.  Whilst some concerns raised about the potential consequences of the case may be on the extreme side, it does serve as a reminder that ‘drop in’ planning applications must be undertaken with care.

The Hillside case involved a site of nearly 30 hectares in Snowdonia National Park which received planning permission in 1967, including a Master Plan for the development of 401 dwellings.  The scheme was built out slowly and under various amendments.  By 2011, at least 14 subsequent planning permissions had been granted for departures from the original Master Plan.  In 2017, the local planning authority indicated its view that, because the developments carried out in accordance with the later planning permissions rendered it impossible to implement the original Master Plan, further development could no longer continue under the 1967 permission.  The current owner of the site sought to confirm the ongoing validity of the original permission by initiating proceedings in the High Court.

At first instance, the High Court determined that, because of development carried out pursuant to subsequent planning permissions granted for alternative residential development, it was now physically impossible to build out the scheme authorised by the 1967 permission and that future development pursuant to that permission would no longer be lawful.  The Court of Appeal agreed that the High Court was perfectly entitled to reach this conclusion.

In that sense, Hillside is simply consistent with a longstanding authority – derived from Pilkington v Secretary of State for the Environment [1973] 1 WLR 1527 (“Pilkington“) – that whilst multiple planning permissions can apply over the same site, where one permission is implemented that is inconsistent with another permission and results in the other permission being incapable of implementation, further development under the other permission would be unlawful. The Pilkington principle is important because it covers a fundamental point in planning law that is not otherwise governed by legislation.

Separate points that arose in the Court of Appeal’s judgment are perhaps less straightforward. 

The first was a side issue explored by the parties at the hearing: whether development already lawfully implemented over part of a scheme could be rendered unlawful by virtue of subsequent development carried out over the unimplemented part of a scheme under a newer permission.  Whilst the Court of Appeal noted the serious implications that such an interpretation might have, because it was concluded that it was unnecessary to deliberate on this point for the purpose of the matter in hand, unhelpfully no clear answer was provided.

The second stems from comments made by one of the Court of Appeal judges , who expressed doubt that a planning permission of the type likely to benefit “a typical modern planning permission for the development of a large estate such as a housing estate” could be construed as separately permitted, independent acts, or that “a developer could lawfully ‘pick and choose’ different parts of the development to be implemented”.  Again, no answer given!

The doubts expressed here have translated into concerns over the validity of ‘drop in’ full planning applications for planning permission for development of a distinct part of the site that already benefits from consent for the wider development.  These are commonly used in situations where changes are sought to an original permission that extend beyond what might be possible through a non-material amendment or minor material amendment application.

Although important questions were left unanswered and concerns left hanging, the comments made in Hillside do not seem to close the door on ‘drop in’ applications as some have suggested.  Rather, they should remind developers to take extra care to ensure that ‘drop in’ applications are done correctly.  With this in mind:

  • a ‘drop in’ application should not conflict with the existing permission for the wider scheme and particular attention should be given to the interface between the existing permission and the new application;
  • any benefits secured under the existing permission should continue to be delivered under the ‘drop in’ application; and
  • a section 106 agreement, or a deed of variation of an existing one, may need to contain a covenant that the existing permission will not be carried out insofar as it relates to the development authorised by the ‘drop in’ permission, once the latter is implemented.

If an appeal against the decision is heard by the Supreme Court, we hope that some clarity will be given on the unanswered questions, and we will share an update if that happens.