This section shall have effect where, on an application for planning permission to develop any land which has a restricted use by virtue of a previous planning permission, permission is refused or granted subject to conditions and an owner of the land serves a purchase notice under section 180 of this Act.
For the purposes of this section, land is to be treated as having a restricted use by virtue of a previous planning permission if it is part of a larger area in respect of which planning permission was previously granted (and has not been revoked) and either—
(a) it remains a condition of the planning permission (however expressed) that that part shall remain undeveloped or be preserved or laid out in a particular way as amenity land in relation to the remainder; or
(b) the planning permission was granted on an application which contemplated (expressly or by necessary implication) that the part should not be comprised in the development for which planning permission was sought, or should be preserved or laid out as aforesaid.
If a copy of the purchase notice is transmitted to the Secretary of State under section 181(3) of this Act the Secretary of State, although satisfied that the land has become incapable of reasonably beneficial use in its existing state, shall nevertheless not be required under section 183(1) of this Act to confirm the notice if it appears to him that the land ought, in accordance with the previous planning permission, to remain undeveloped or, as the case may be, remain or be preserved or laid out as amenity land in relation to the remainder of the large area for which that planning permission was granted.