21Commencement
(1)This Act comes into force in accordance with provision made by order by the Secretary of State.
(2)Different provision may be made under subsection (1) for different purposes.
In particular, different transitional provision (made by virtue of section 18(1)) may be made for UK heavy goods vehicles and non-UK heavy goods vehicles.
(3)Subsection (1) does not apply to sections 17 to 22 (which accordingly come into force on the day on which this Act is passed).