QBD 7 November 1991. The appellant P bought a site which included a dwelling and a boiler house. Planning permission was obtained for alterations and an extension to the house. Works were carried out to the boiler house, without planning permission, so that it became capable of being used as a residence. P moved into this while the work on the main house was completed and in 1988 it was let to tenants as a separate unit. The council served an enforcement notice alleging breach of planning control in the making of a material change of use of the land from use for one dwelling to two. The inspector found that the first use of the boiler house by P was ancillary to the enjoyment of the unit but the use of it by tenants was as an independent unit. He therefore concluded that there had been a material change of use. P claimed that as the boiler house had been used as a separtate dwelling since 1985 the immunity offered under Town and Country Planning Act 1990 s172(4)(c) applied. The appea