38For section 20(12) of that Act (variation and revocation of orders for periodical payments) there shall be substituted—
“(12)An application under this section may be made—
(a)where it is for the variation or revocation of an order under section 2, 6, 7 or 19 of this Act for periodical payments, by either party to the marriage in question; and
(b)where it is for the variation of an order under section 2(1)(c), 6 or 7 of this Act for periodical payments to or in respect of a child, also by the child himself, if he has attained the age of sixteen.”