s 97 Power to revoke or modify planning permission or permission in principle .
(1) If it appears to the local planning authority that it is expedient to revoke or modify— (a) any permission (including permission in principle) to develop land granted on an application made under this Part or, in relation to England, Part 13 , or (b) any permission in principle granted by a development order, the authority may by order revoke or modify the permission to such extent as they consider expedient. (2) In exercising their functions under subsection (1) the authority shall have regard to the development plan and to any other material considerations. (3) The power conferred by this section may be exercised— (a) in the case of planning permission that relates to the carrying out of building or other operations, at any time before those operations have been completed; (b) in the case of planning permission that relates to a change of the use of any land, at any time before the change has taken place. (4) The revocation or modification of planning permission for the carrying out of building or other operations shall not affect so much of those operations as has been previously carried out. (5) References in this section to the local planning authority are to be construed in relation to development consisting of the winning and working of minerals as references to the mineral planning authority, . . .. (6) Part II of Schedule 5 shall have effect for the purpose of making special provision with respect to the conditions that may be imposed by an order under this section which revokes or modifies permission for development— (a) consisting of the winning and working of minerals; or (b) involving the depositing of refuse or waste materials. (7) Subsection (1) does not permit the revocation or modification of the condition under paragraph 13 of Schedule 7A (the biodiversity gain condition), subject as follows. (8) The Secretary of State may by regulations make provision— (a) for the condition under paragraph 13 of Schedule 7A to apply in relation to the modification of planning permission under this section, subject to such modifications as may be specified in the regulations; (b) for planning permission modified under this section to be subject to other conditions relating to meeting the biodiversity gain objective referred to in paragraph 2 of Schedule 7A (including conditions of a kind referred to in paragraph 20(3) of that Schedule). (9) Subsection (1) does not permit the revocation or modification of the condition under section 90B (condition relating to development progress reports in England).