5.—(1) Until 27th July 1992 or the date on which section 10 of the 1991 Act is brought fully into force, if later—
(a)an enforcement notice which relates to a failure to comply with any condition or limitation relating to the carrying out of any operation specified in section 171B(1) of the 1990 Act, in, on, over or under land and subject to which planning permission was granted for the development of that land, may be issued only within the period of four years from the date of the breach; and
(b)nothing in section 171B(3) of the 1990 Act prevents an enforcement notice which relates to a breach of planning control (other than a breach falling within section 171B(1) or (2) of the 1990 Act or paragraph (a) above) being issued where it appears to the local planning authority that the breach occurred after the end of 1963.
(2) Subject to paragraph (3), the commencement of paragraph (b) of section 171B(4) shall not permit the taking of further enforcement action in respect of any breach of planning control where, immediately before the commencement of that paragraph, the local planning authority could not have issued an enforcement notice relating to that breach.
(3) Paragraph (2) does not apply where any proceedings under the 1990 Act in respect of the breach pursuant to the issue or purported issue of an enforcement notice by the local planning authority have not been finally determined before the commencement of paragraph (b) of section 171B(4).