Impey v Secretary of State for the Environment and Lake District Special Planning Board; Lake District Special Planning Board v Secretary of State for the Environment and Impey [1981] JPL 363
Impey is a leading authority on when a material change of use can begin. The case concerned former dog-breeding premises being converted for residential use and whether actual residential occupation had to begin before the change of use could be said to have occurred.
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- Neutral citation
- [1981] JPL 363; (1984) 47 P&CR 157
- Court
- High Court, Queen's Bench Division, Divisional Court
- Judge
- Donaldson LJ is expressly quoted in later authorities; the full constitution has not been independently verified
Actual occupation is not always required
The Divisional Court rejected an approach under which residential change of use could only occur once someone had actually begun living in the premises. Physical conversion can, in an appropriate case, take the process far enough for the material change of use to have occurred before ordinary residential occupation begins.
The physical state and intended use must be considered together
Donaldson LJ explained that the physical state of the premises is very important but not decisive. Actual use, intended use and attempted use are likewise important but not individually decisive. The matter has to be looked at in the round as a question of fact and degree.
The judgment suggested that whether premises have become usable for the new use may be an important point in deciding when the change has occurred.
Why Impey still matters
The Supreme Court expressly relied on Impey in Welwyn Hatfield v Secretary of State [2011] UKSC 15. It remains particularly relevant to certificates of lawfulness, enforcement appeals and permitted-development cases where the precise date on which a new use began is critical.
However, Impey should not be treated as saying that physical works alone automatically establish a new use. The circumstances, state of the premises and actual or intended activity all need to be considered together.
One case, two captions
The reports and later decisions refer to the proceedings under both Impey v Secretary of State for the Environment and Lake District Special Planning Board v Secretary of State and Impey. They are treated here as one combined authority rather than two separate cases.
Source limitation
Planning Geek does not currently hold the original report. The relevant passages are reproduced and approved by the Supreme Court in Secretary of State v Welwyn Hatfield Borough Council [2011] UKSC 15, and the case continues to be applied in modern planning decisions.
Impey Case Law Page Updated: 11th September 2026