§ 12. "That, as from the date on which the agreement made on the twentieth day of March, nineteen hundred and thirty-nine, between His Majesty's Government in the United Kingdom and the Government of India comes into force under Article 16 thereof, the Ottawa Agreements Act, 1932, and any other enactment relating to customs which amends or relates to that Act, shall have effect as if that Agreement were substituted for the Agreement set out in Part VI of the First Schedule to that Act."