If it appears to the local planning authority that it is expedient to revoke or modify any listed building consent granted on an application under this Act, the authority may by order revoke or modify the consent to such extent as they consider expedient.

In performing their functions under subsection (1) the local planning authority shall have regard to the development plan and to any other material considerations.

The power conferred by this section to revoke or modify listed building consent in respect of any works may be exercised at any time before those works have been completed, but the revocation or modification shall not affect so much of those works as has been previously carried out.