If, in the case of a variation of the terms of a regulated tenancy, there is a failure on the part of the landlord to observe any of the requirements of section 42, 43 or 44 of this Act, any excess of the rent payable under the terms as varied over the terms without the variation shall be irrecoverable from the tenant.

If, in the case of the grant of a tenancy, there is a failure on the part of the landlord to observe any of the requirements of section 42, 43 or 44 of this Act, any excess of the rent payable under the tenancy so granted (for any contractual or any statutory period of the tenancy) over the previous limit shall be irrecoverable from the tenant.

In subsection (2) above the " previous limit" shall be taken to be the amount which (taking account of any previous operation of this section) was recoverable by way of rent for the last rental period of the previous tenancy of the dwelling-house, or which would have been so recoverable if all notices of increase authorised by the Act of 1971, or by section 36(2) of this Act, had been served.

A default in complying with subsection (5)(c) of section 43 of this Act shall not apply to rent for any rental period after the default is made good, and, if a rent agreement with a tenant having security of tenure is put into effect earlier than the date when it is provided under section 43 of this Act that it may take effect, such a default shall not affect the rent for any rental period beginning after that date.

Section 31 of the Act of 1971 (enforcement provisions) shall apply as if any amount made irrecoverable by this section were irrecoverable by virtue of Part III of that Act.