(1) On the appointed day Section five of the Finance (No. 2) Act, 1945, shall cease to have effect and Section thirteen of the Finance Act, 1920, shall have effect as if the following proviso were inserted at the end of paragraph 6 of the Second Schedule to that Act, that is to say: Provided that, notwithstanding anything in the preceding provisions of this paragraph, the duty to be charged in respect of a vehicle falling within this paragraph which derives its motive power wholly from an internal combustion engine worked by a cylinder or cylinders shall be at a rate of five pounds per vehicle.