Section 18(1): amended, on 24 October 2019, by section 181(1) of the Statutes Amendment Act 2019 (2019 No 56).
Section 18(1)(aa): inserted, on 24 October 2019, by section 181(2) of the Statutes Amendment Act 2019 (2019 No 56).
Section 18(2)(ab): inserted, on 16 December 1988, by section 2 of the Winston Churchill Memorial Trust Amendment Act 1988 (1988 No 220).