Hillside Parks V Snowdonia National Park

by Marco Mauro

1 December 2022

This article explores the importance of the recent landmark judgement handed down from the Supreme Court regarding Hillside Parks Ltd (“Developer”) v Snowdonia National Park Authority (“Authority”), relating to planning law and the ability to use multiple planning permissions on the same piece of land.


In 1967, Merioneth County Council granted planning permission for 401 dwellings, in respect of a development site known as “Balkan Hill”, which was located within 29 acres of land near Aberdyfi in Snowdonia National Park. The development was meant to be constructed in accordance with what was referred to as the ‘Master Plan’, which was at the heart of the dispute.

Since the original planning permission was granted, the ownership of the Balkan Hill site has changed twice and throughout that time the development site has seen very little progress. Furthermore, none of the houses had been built (a grand total of 41) in accordance with the Master Plan. Due to numerous issues, the developer of the Balkan Hill site had applied for and had been granted a series of additional planning permissions permitting development, which has now taken place on parts of the site. This resulted in development straying from the original Master Plan and resulted in roads being built in areas designated for houses, and houses being built in areas designated for roads. This therefore posed the question as to whether the developer is entitled to carry out further development in accordance with the other permissions (making the 1967 permission redundant) or whether the developer is still entitled to carry out further development pursuant to the original 1967 permission.

There have been various historical disputes regarding the original 1967 permission. This included in 1985, a dispute which arose surrounding the validity of the 1967 permission due to the fact the permission had been granted subject to one specified condition, namely that there needed to be a water supply to the site before any work could be carried out. However it was held in a trial in the High Court before Drake J that this condition had been met and that lawful development had taken place within the statutory time limit. Additionally, Drake J made the statement that due to the fact the 1967 development had already begun, it ‘may lawfully be completed at any time in the future’. At the time of the trial, there doesn’t appear to have been any consideration given to any legal analysis regarding variations of the 1967 permission, which was largely due to the lack of powers available to the local planning authority to amend planning permissions which had been previously granted.

Between the years of 1987 and 2017, there were a grand total of eight subsequent planning permissions granted. Some of the permissions which were granted, were described as ‘variations’ of the original 1967 permission. However, in 2017, another dispute arose regarding the validity of the 1967 permission and it was held by HHJ Keyser QC in the High Court that due to the result of the physical alterations that had taken place since 1987, it was deemed physically impossible to complete the development in accordance with the 1967 permission meaning that any further development of the Balkan Hill site would be unlawful. The case was put forward for appeal, however the Court of Appeal dismissed the appeal due to the reasons stated above.


Supreme Court Judgment

Fast forward to this year, and the case was granted permission to appeal to the Supreme Court, on the issue of ‘whether any further development could lawfully be carried out under the 1967 permission, but not on the res judicta issue.’ The case was heard on 4 July 2022 before Lord Reed, Lord Briggs, Lord Sales, Lord Leggatt and Lady Rose, with the judgment announced on 2 November 2022. The Supreme Court dismissed the Developer’s appeal stating “the development on part of the Site under the Post-1987 Permissions, which departed from the 1967 Permission and was inconsistent with the Master Plan, has made it physically impossible and so unlawful to carry out any further development under the 1967 Permission.’ It was concluded that the post-1987 permissions were ‘departures from, not variations of’ the original 1967 permission. This judgment re-affirms what is known as the Pilkington principle (derived from the case of Pilkington v Secretary of State for the Environment [1973] 1 WLR 1527) which essentially means that whilst multiple planning applications can be made in relation to the same piece of land (even if they are inconsistent with each other), once one of those applications is acted upon and development is carried out making it physically impossible to comply with the requirements of the other permissions, those other permissions are deemed invalid. However, whilst the Developer put forward the argument of the principle of abandonment, it was held that the decision is based upon the ‘physical impossibility of carrying out that which was authorised in the earlier planning permission.’

It was also highlighted that the Pilkington principle should not be pressed too far and should therefore only be engaged when there has been a material departure from the permission granted, which is entirely a question of fact and degree (Lever finance Ltd v Westminster (City) London Borough Council [1971] 1 QB 222, 230).


What does this mean for the future of planning?

This case highlights the importance of planning law issues relating to the implementation of subsequent planning permissions on the same piece of land. This has proven to be hugely instrumental regarding large development sites, whereby the ‘slotting in’ of planning applications to change various aspects of the development site has always caused significant controversy.

The Supreme Court has provided clarity on some of the points raised by the courts below. In particular, if a development is not completed fully in accordance with a planning permission it does not result in the whole development being unlawful and the failure to complete a development does not make what has been constructed unlawful. Also, that the Pilkington principle should not be pressed too far. However, the Supreme Court only considered the position in relation to full planning permissions and not outline or hybrid permissions.

There are still tricky issues for practitioners to grapple with and following this judgment, it will be necessary to continue finding methods to work round any issues presented by the use of multiple planning permissions and also to serve as caution about adopting a careful and logical approach concerning planning permission on a site.

This article was prepared by Sidonie Emerson-Quorn.
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