19. Article 12 of the principal Order (development requiring planning permission) shall be renumbered as paragraph (1) of that Article and after that paragraph there is inserted—
“(2) Where planning permission to develop land has been granted for a limited period, planning permission is not required for the resumption, at the end of that period, of its use for the purpose for which it was normally used before the permission was granted.
(3) Where by a development order planning permission to develop land has been granted subject to limitations, planning permission is not required for the use of that land which (apart from its use in accordance with that permission) is its normal use.
(4) Where an enforcement notice has been issued in respect of any development of land, planning permission is not required for its use for the purpose for which (in accordance with the provisions of this Part) it could lawfully have been used if that development had not been carried out.
(5) In determining for the purposes of paragraphs (2) and (3) what is or was the normal use of land, no account shall be taken of any use begun in contravention of this Part.”.