3Section forty-two of the Finance Act, 1947 (which as amended by subsection (3) of section seven of the Finance (No. 2) Act, 1947, restricts the profits tax chargeable in the case of building societies to six per cent. of their profits, computed as therein mentioned), shall, in relation to any chargeable accounting period ending after the end of the year nineteen hundred and fifty-one, have effect as if the words " two per cent." were substituted for the words " six per cent. "