A notice served under section 29 of the Income Tax Act 1952 (re-enacted in section 17 of this Act) on the Postmaster General before 1st October 1969 shall, if it has not been complied with before that date, be deemed to have been served on the Director of Savings; and section 17(1) of this Act shall, in its application to the National Savings Bank, have effect as if the reference to interest paid or credited by the Director of Savings included, as regards any period before the said date, a reference to interest paid or credited by the Postmaster General to depositors.