Hillside Parks Ltd v Snowdonia National Park Authority [2022] UKSC 30
Hillside incompatible planning permissions is the modern Supreme Court authority on overlapping permissions and when later development makes an earlier planning permission incapable of further implementation.
The case is not really about abandoning a permission. The central question is physical compatibility: can the development authorised by the earlier permission still be carried out after what has subsequently been built?
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- Neutral citation
- [2022] UKSC 30
- Court
- Supreme Court of the United Kingdom
- Judgment date
- 2nd November 2022
- Judge
- Lord Reed, Lord Briggs, Lord Sales, Lord Leggatt and Lady Rose
What Hillside decided
The dispute concerned a large 1967 permission for 401 dwellings in Snowdonia. Over many years later permissions had authorised materially different development on parts of the site.
The Supreme Court held that those later developments had made it physically impossible to complete the original 1967 scheme in accordance with its approved masterplan. The appeal was dismissed.
There is no general doctrine of abandoning planning permission
The court rejected the language of abandonment as the correct legal explanation. An extant permission does not disappear simply because the owner no longer intends to complete it.
The real issue is whether later development has made further implementation of the earlier permission physically impossible.
Planning Geek’s guide to extant planning permission explains the distinction.
An integrated permission is ordinarily one scheme
Where a permission authorises a single integrated development across a site, it is not ordinarily possible to treat each plot as if it were a separate independent permission unless the consent itself provides for that degree of severability.
In Hillside, the masterplan was fundamental to the permission. Materially inconsistent development on parts of the site meant that the approved whole could no longer be completed.
Later incompatible development does not retrospectively criminalise earlier works
A particularly important qualification is that development lawfully carried out under an earlier permission does not become unlawful retrospectively merely because later development makes completion of the rest impossible.
The consequence is prospective: further works which depend on the now-impossible earlier scheme cannot simply continue to rely on it.
Minor departures are not necessarily fatal
The court did not say that every discrepancy between built development and an approved plan destroys the permission. Whether a departure is material is a question of fact and degree.
The focus is on whether the later development is sufficiently inconsistent with the authorised scheme that completion according to the permission is no longer physically possible.
A later permission can deliberately replace the planning position
Nothing prevents a developer seeking a fresh permission designed to authorise a coherent revised scheme across the whole or relevant part of the site.
But that outcome depends on the objective terms of the later permission. Private intentions or informal correspondence cannot transform a permission which does not, on its face, perform that function.
Why Hillside matters
The case is essential whenever a site has several overlapping permissions, especially phased housing schemes and long-running developments where later consents have changed roads, plots, buildings or infrastructure.
The practical exercise is to compare the permissions and the development actually carried out, then ask whether the earlier authorised scheme remains physically capable of completion.
Read the full Hillside judgment
The full Supreme Court judgment is held in the Planning Geek case law library. Gold Members can open the protected PDF below.
Hillside Case Law Page Updated: 10th September 2026