In the proviso to section 2(1) of the [1950 c. 21.] Miscellaneous Financial Provisions Act 1950 (which, as amended by section 7(1) of the [1964 c. 9.] Public Works Loans Act 1964, restricts the total principal amount outstanding in respect of advances to the Exchequer of Northern Ireland under the said section 2 to forty million pounds) for the words " forty million pounds " there shall be substituted the words " seventy million pounds ".