Section 9

where, after the fair rent of any controlled premises has been determined in accordance with this Act, the rate payable by the landlord in respect of such controlled premises has been increased; or

where since the date by reference to which the fair rent of any controlled premises is determined the landlord has, in connection with the restoration, the improvement or the making of structural alteration of the premises, incurred expenditure (not including expenditure on decoration or ordinary repairs), subject to the following subsections, the fair rent of any controlled premises may be increased in the case mentioned in paragraph (a) to the extent which shall not exceed the amount of the increase of rates payable in respect of such controlled premises, and in the case mentioned in paragraph (b) to the extent which shall not exceed such sum as will allow the landlord a reasonable return in respect of such expenditure.

Nothing in this section shall be deemed to relieve a landlord from the necessity of determining the tenancy according to law prior to increasing the rent.

Nothing in this section shall apply to any subtenancy arising from the subletting of any part of any premises, unless the landlord by virtue of notification under section 20 (2) treats such subtenancy as joint-tenancy.