This section applies to any purchase notice served on or after 5th November 1964 (whether before or after the passing of this Act) in respect of land within the metropolitan region, or served on or after 5th August 1965 (whether before or after the passing of this Act) in respect of land which, at the date of service of the notice, is within a controlled area as defined in section 81(2) of this Act outside the metropolitan region, where either—
(a) planning permission for the carrying out on that land, or part of it, of development to which section 74 of this Act applies was granted before 5th August 1965. but by virtue of paragraph 1(4) of Schedule 12 to this Act that planning permission is for the time being deemed not to have effect; or
(b) the purpose for which that land, or part of it, is or was used at the date of service of the notice, or was last used before that date, is or was that of a building containing office premises.
In relation to a purchase notice to which this section applies, the provisions of this Act shall have effect as if, after subsection (4) of section 183 of this Act, there were inserted the following subsection— and as if, in subsection (5) of that section, after the words " by virtue of " there were inserted the words " subsection (4A) of this section or "
Where in pursuance of subsection (4A) of the said section 183 (as modified by subsection (2) of this section) the Secretary of State has determined not to confirm a purchase notice to which this section applies, and on a subsequent date the land to which that notice related ceases to be within an area to which section 74 of this Act applies—
(a) a further purchase notice may be served on or after that date in respect of the planning decision to which the previous notice related ; and
(b) for the purposes of any regulations made under this Act as to the time within which a purchase notice may be served, the service of such a further purchase notice shall not be treated as out of time if it is served within the period which would be applicable in accordance with those regulations if the planning decision referred to in the preceding paragraph had been made on that subsequent date.
In determining, for the purposes of subsection (1)(b) of this section, for what purpose any land is used, or was last used, as the case may be, no account shall be taken—
(a) of any use in accordance with planning permission granted for a limited period ; or
(b) of any use in respect of which, before the date of service of the purchase notice, an enforcement notice had been served and had become effective; or
(c) of any use of land at a time when it is or was not covered by a building.
For the purposes of this section " office premises " has the meaning assigned by section 73(4) of this Act and this section shall have effect as if it were included in sections 73 to 86 of this Act.
Notwithstanding subsection (5) of this section, subsection (3) of this section shall not cease to have effect at the end of the period mentioned in section 86 of this Act; and in relation to any land which, immediately before the end of that period, is land within an area to which section 74 of this Act applies, any reference in that subsection to the date on which the land ceases to be within such an area shall be construed as a reference to the end of that period.