2Any tariff fixed under section 37(3) of the [1947 c. 54.] Electricity Act 1947 or section 22(1) of the [1979 c. 11.] Electricity (Scotland) Act 1979 which is effective on the day appointed for the coming into force of section 18 of this Act shall have effect as if fixed under subsection (1) of the said section 18; and the provisions of Part I of this Act shall apply accordingly.