For the purposes of pool betting duty on bets made at any time by reference to any event taking place after 31st March 1974, section 7(1) of the Betting and Gaming Duties Act 1972 and section 18(1) of the Miscellaneous Transferred Excise Duties Act (Northern Ireland) 1972 (under which the amount of the duty is 33⅓ per cent. of the amount on which the duty falls to be computed) shall each have effect with the substitution for the words “33⅓ per cent.” of the words “ 40 per cent. ”, except in the of bets made by way of pool betting in respect of a competition prize held by—