18.—(1) Subject to paragraphs (3) and (4), if a local planning authority is satisfied that it is expedient to do so, it may by order revoke or modify an express consent.
(2) Without prejudice to the generality of paragraph (1), a local planning authority may have regard to any material change in circumstances that has occurred since the consent was granted.
(3) An order under paragraph (1) shall not take effect without the approval of the Secretary of State.
(4) The power to make an order under this regulation may be exercised—
(a)in a case which involves the carrying out of building or other operations, at any time before those operations have been completed;
(b)in any other case, at any time before the display of advertisements is begun.
(5) When an authority submits an order under paragraph (1) to the Secretary of State for approval, it shall serve notice on the person who applied for the express consent, the owner and any occupier of the land affected and any other person who, in the authority's opinion, will be affected by the order, specifying a period of at least 28 days from the date of service of the notice within which objection may be made.
(6) If, within the period specified in the notice, an objection to the order is received by the Secretary of State from any person on whom notice was served, the Secretary of State shall, before considering whether to approve the order, give to that person and to the local planning authority an opportunity of appearing before and being heard by a person appointed by her.
(7) In considering whether to approve an order submitted to her under this regulation, the Secretary of State may have regard to any material change in circumstances that has occurred since the consent was granted.
(8) The Secretary of State may approve an order submitted to her under this regulation either without modification or subject to such modifications as she considers expedient.
(9) Where the Secretary of State approves an order submitted to her under this regulation, the local planning authority shall, within 14 days of the receipt of the Secretary of State's decision, send to every person notified under paragraph (5) notice of the Secretary of State's approval.
(10) An order which has been approved under this regulation shall take effect on the day after that on which the local planning authority complies with the requirements of paragraph (9).
(11) Where an order is made in a case to which paragraph (4)(a) applies, the revocation or modification of consent shall not affect such operations as have been carried out before the date on which, in accordance with paragraph (5), notice of the order is served.