Sections five and eight of the Coal Mines Act, 1930, shall have effect subject to the amendments specified in the Seventh Schedule to this Act, and Part I of that Act (which, as continued by subsequent enactments, is limited to expire on the thirty-first day of August nineteen hundred and thirty-eight) shall, as amended by this Act, continue in force until the thirty-first day of December nineteen hundred and forty-two, and no longer unless Parliament otherwise determines.