Subject to sections 4, 6, 7 and 8 of the principal Act (which make provision as to the exercise of planning functions in National Parks, enterprise zones, urban development areas and housing action areas) and to the following provisions, outside Greater London the functions of a local planning authority under sections 7 to 26, 38, 42, paragraph 2(2) of Schedule 1 and Schedule 2 shall be exercised by the district planning authority.