The provisions of Part III of this Schedule (which are derived from Schedule 1 to the Clean Air Act 1956 as that Schedule had effect immediately before the date mentioned in paragraph 8(1) of this Schedule) shall apply in substitution for Schedule 1 to this Act in relation to any such order; and references in this Act, as it applies in relation to any such order, to Schedule 1 to this Act or to any specified provision of that Schedule shall be read as referring to Part III of this Schedule or the corresponding provision of that Part (as the case may be).