A tenant shall not be entitled to compensation under section 16 of this Act in respect of a tenant’s improvement which consists of planning permission unless—
the landlord has given his consent in writing to the making of the application for planning permission,
that consent is expressed to be given for the purpose—
of enabling a specified physical improvement falling within paragraph (a) of section 15 of this Act lawfully to be provided by the tenant, or
of enabling the tenant lawfully to effect a specified change of use, and
on the termination of the tenancy, the specified physical improvement has not been completed or the specified change of use has not been effected.
Any such consent may be given either unconditionally or on condition that the tenant agrees to a specified variation in the terms of the tenancy.
The variation referred to in subsection (2) above must be related to the physical improvement or change of use in question.