The Secretary of State may by order authorise, subject to such restrictions and conditions as may be specified by or under the order, the use on roads—
(a) of special motor vehicles or trailers, or special types of motor vehicles or trailers, which are constructed cither for special purposes or for tests or trials,
(b) of vehicles or trailers, or types of vehicles or trailers, constructed for use outside the United Kingdom,
(c) of new or improved types of motor vehicles or trailers, whether wheeled or wheelless, or of motor vehicles or trailers equipped with new or improved equipment or types of equipment, and
(d) of vehicles or trailers carrying loads of exceptional dimensions;
and nothing in section 40 of this Act shall prevent the use of such vehicles, trailers, or types as aforesaid in accordance with the order.
The Secretary of State may by order make provision for securing that, subject to such restrictions and conditions as may be specified by or under the order, regulations under the said section 40 shall have effect in their application to such vehicles, trailers and types thereof as are mentioned in subsection (1) above subject to such modifications or exceptions as may be specified in the order.
Any order under this section may be varied or revoked by a subsequent order of the Secretary of State.
The powers conferred by this section on the Secretary of State to make orders shall be exercisable by statutory instrument except in the case of orders applying only to specified vehicles or to vehicles of specified persons.