Local planning authorities (LPAs) are under a duty to determine which parts of their area are of "special architectural or historic interest the character or appearance of which it is desirable to preserve or enhance" when designating conservation areas.

Conservation area consent is required for demolition of an unlisted building in a conservation area.

A developer owned a 1930s neo-Georgian building and submitted a planning application for demolition and redevelopment. A local campaign was set up to prevent demolition but English Heritage refused to list the building and the LPA refused to put it on the list of buildings of local interest.

The planning officer's report recommended that permission be granted but the planning committee rejected the recommendation and refused the application on the basis of the impact of the development.

The developer gave six weeks' prior notice of demolition under the Building Act 1984, but the LPA designated the Limehouse Cut Conservation Area some four weeks later. In view of the imminent threat of demolition there was no consultation with the developer.

The developer challenged the decision on two grounds. The court refused to quash the decision not to consult, but did quash the decision to designate the conservation area. There were a number of errors in the planning officer's report and members of the committee ignored material considerations but took into account immaterial considerations, namely the desire to frustrate the demolition. Members had been misled.

Trillium (Prime) Property GP Ltd v London Borough of Tower Hamlets