Hillside Parks Ltd sought to rely on a 1967 planning permission for 401 dwellings despite decades of development departing from the original Master Plan under separate permissions. The Supreme Court held that subsequent inconsistent development rendered the 1967 permission physically impossible to implement, and dismissed the appeal.
Background
The appeal concerned a 29-acre site known as ‘Balkan Hill’ near Aberdyfi in the Snowdonia National Park. In January 1967, full planning permission was granted for the development of 401 dwellings in accordance with a detailed ‘Master Plan’ showing the proposed location of each house and the layout of an internal road system (‘the 1967 permission’). Over more than fifty years, only 41 houses were built on the site — none in accordance with the Master Plan. Instead, the developer obtained a series of additional specific planning permissions for development which materially departed from the original scheme.
In 1987, Drake J had declared that the 1967 permission remained valid and could lawfully be completed at any time in the future, treating the earlier additional permissions as ‘variations’ of the 1967 permission. After 1987, the developer continued to build in ways that departed substantially from the Master Plan, obtaining eight further permissions. In May 2017, the Snowdonia National Park Authority asserted that the 1967 permission could no longer be implemented, prompting the developer to bring proceedings seeking declarations that the permission remained valid.
The Issue(s)
The central question was whether further development could lawfully be carried out under the 1967 permission, or whether development carried out pursuant to subsequent independent planning permissions had rendered the 1967 permission physically impossible to implement. Three subsidiary issues arose:
1. Abandonment
Whether the principle in Pilkington v Secretary of State for the Environment [1973] 1 WLR 1527 rested on a doctrine of abandonment, such that only conduct leading a reasonable person to conclude the right had been abandoned would extinguish the permission.
2. Severability of multi-unit permissions
Whether a planning permission for a multi-unit development such as a housing estate should be interpreted as severable into discrete permissions for each individual building, allowing the developer to build any sub-set of units alongside inconsistent development authorised by other permissions.
3. The ‘variation’ argument
Whether the post-1987 permissions were properly construed as modifications of the 1967 permission rather than independent permissions, such that the 1967 permission (as varied) remained capable of further implementation.
The Court’s Reasoning
Rejection of the abandonment argument
The Supreme Court firmly rejected any suggestion that the Pilkington principle rested on a doctrine of abandonment. Lord Widgery CJ had expressly stated in Pilkington:
My views on this matter are not based on any election on the part of Mr Pilkington; they are not based on any abandonment of an earlier permission … I base my decision on the physical impossibility of carrying out that which was authorised in [the earlier planning permission].
The Court confirmed the House of Lords’ decision in Pioneer Aggregates (UK) Ltd v Secretary of State for the Environment [1985] AC 132, where Lord Scarman held there was no room for a principle of abandonment in planning law, as Parliament had provided a comprehensive code of planning control. Lord Scarman had observed that introducing such a doctrine would be inconsistent with section 75(1) of the Town and Country Planning Act 1990, which provides that planning permission enures for the benefit of the land. The Court endorsed Lord Scarman’s reasoning that the Pilkington decision was:
certainly a common sense decision, and, in my judgment, correct in law
and that its rationale was physical impossibility, not abandonment.
The Pilkington principle restated
The Court articulated the underlying principle as follows:
In essence, the principle illustrated by the Pilkington case is that a planning permission does not authorise development if and when, as a result of physical alteration of the land to which the permission relates, it becomes physically impossible to carry out the development for which the permission was granted (without a further grant of planning permission).
Importantly, the test of physical impossibility applies to the whole site covered by the unimplemented permission, not just the part on which the landowner now wishes to build. The Court also clarified that the test concerns what has actually been done on the land, not what is authorised by the terms of the implemented permission.
Rejection of severability
The Court overruled F Lucas & Sons Ltd v Dorking and Horley Rural District Council (1964) 17 P & CR 116, which had treated a multi-unit permission as severable into discrete permissions for each individual house. The Court held that Winn J’s analysis in that case was wrong because it failed to recognise that:
planning permission for a multi-unit development is applied for and is granted for that development as an integrated whole. In deciding whether to grant the permission, the local planning authority will generally have had to consider, and may be taken to have considered, a range of factors relevant to the proposed development taken as a whole, including matters such as the total number of buildings proposed to be constructed, the overall layout and physical appearance of the proposed development, the infrastructure required, its sustainability in planning terms and whether the public benefits of the proposed development as a whole outweigh any planning objections.
The Court drew a critical distinction between two propositions: (i) that a planning permission is not spatially severable into separate permissions for discrete parts of the site, and (ii) that development is only authorised if the whole development is carried out. Rejection of the second proposition (a condition subsequent) does not undermine the first. The Court held that when permission is granted for a multi-unit development, it authorises each stage for so long as it remains practically feasible for the whole development to be implemented.
The ‘holistic approach’ and the Sage case
The Court addressed and limited the reach of obiter remarks by Lord Hobhouse in Sage v Secretary of State for the Environment [2003] UKHL 22, which had been read by some as meaning that failure to complete a development fully in accordance with a permission renders the whole development unlawful. The Court disagreed with this reading, noting that section 95(5) of the 1990 Act specifically provides that a completion notice does not affect permission so far as development already carried out is concerned. The Court stated:
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. But (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.
Materiality of departures
The Court held that not every departure from a permitted scheme triggers the Pilkington principle. Only material departures have this effect. The ordinary presumption is that a departure must be material in the context of the scheme as a whole, which is a matter of fact and degree.
The ‘variation’ argument rejected on the facts
The Court accepted in principle that a planning permission could be framed as a modification of an earlier permission rather than an independent grant. However, this would ordinarily require an application accompanied by a plan showing how the proposed changes were incorporated into a coherent design for the whole site. The Court stated:
Mere use of the ‘variation’ label by itself is not sufficient to show how the new permission ought properly to be interpreted, when read as a whole and having regard to the relevant context.
Examining each of the post-1987 permissions, the Court found that none could properly be construed as modifying the 1967 permission. Even those described as ‘variations’ related only to specific sites within Balkan Hill and were not accompanied by revised plans for the whole site. The permissions referring to plot numbers on the Master Plan used those numbers merely as geographical references, not as indications that the development was intended to modify the Master Plan scheme. Permission G was plainly inconsistent with the 1967 scheme, with houses built across an estate road that served as an access route to the entire northern part of the site.
The Court observed that an objective observer looking at the planning history would have seen:
a pattern of development significantly different from that authorised by the 1967 permission and would see that every house built in the 40 years since it was granted had been built in accordance with a subsequent specific planning permission. There was nothing in this history which showed that the Developer still intended to carry out any development in accordance with the 1967 permission.
Practical Significance
This decision is of major importance in planning law for several reasons. First, it authoritatively restates the Pilkington principle as one of physical impossibility, firmly rejecting any doctrine of abandonment in planning law. Second, it overrules Lucas and establishes that a planning permission for a multi-unit development is not severable into discrete permissions for individual units. Third, it clarifies that while failure to complete a development does not retrospectively render completed works unlawful, a permission ceases to authorise further development once compliance becomes physically impossible. Fourth, it confirms that only material departures from a permitted scheme engage the Pilkington principle. Fifth, it establishes that while a ‘variation’ permission modifying an earlier scheme is possible in principle, it requires proper documentation — including a plan showing how the modification integrates into a coherent whole-site design — and mere labelling as a ‘variation’ is insufficient. The decision highlights the practical consequences for developers of the limited statutory powers to amend existing permissions, while noting that a fresh permission covering the whole site with necessary modifications remains available as a route forward.
Verdict: The appeal was dismissed. The Supreme Court upheld the decisions of the courts below, holding that the 1967 planning permission had been rendered incapable of further implementation by development carried out on the Balkan Hill site pursuant to subsequent independent planning permissions which materially departed from the Master Plan. The Developer’s claim for declarations that the 1967 permission remained valid and could be carried on to completion was refused.
Source: Hillside Parks Ltd v Snowdonia National Park Authority [2022] UKSC 30
