If an approved dwelling is a flat in a block of flats of four or more storeys, the amount of the annual exchequer subsidy payable under this Part of this Act shall be the amount payable under the foregoing sections of this Act plus—
in the case of a flat in a block of flats of four storeys, eight pounds,
in the case of a flat in a block of flats of five storeys, fourteen pounds,
in the case of a flat in a block of flats of six or more storeys, twenty-six pounds, increased by one pound fifteen shillings for each storey by which the block exceeds six storeys.
Section seven of the Housing (Financial Provisions) Act, 1958 (which authorises the payment of subsidies for expensive sites), shall apply in relation to an approved dwelling as defined in this Part of this Act as it applies in relation to an approved dwelling as defined in Part I of that Act.