(4) Where any land is designated by a development plan as subject to compulsory acquisition by the appropriate local authority (not being land comprised in an area defined by the plan as an area of comprehensive development) then if permission is granted under Part III of this Act for any development of the land so designated, or any part thereof, and that development is carried out in accordance with the permission so granted, the development plan shall have effect as if the land to which the permission relates were not designated as subject to compulsory acquisition: