If a plating certificate has been issued for a goods vehicle to which section 46(1) of this Act or subsection (1) above applies, but does not specify a maximum laden weight for the vehicle together with any trailer which may be drawn by it, any person who on or after the relevant date within the meaning of the said section 46(1) or, as the case may be, the day appointed under the said subsection (1) uses the vehicle on a road for drawing a trailer, or causes or permits it to be so used, shall be guilty of an offence.
Any person who uses on a road, or causes or permits to be so used, a goods vehicle when an alteration has been made to the vehicle or its equipment which is required by regulations or directions under section 48 of this Act to be, but has not been, notified to the Secretary of State shall be guilty of an offence.
In any proceedings for an offence under subsection (3) above, it shall be a defence to prove that the regulations were not, or, as the case may be, the alteration was not, specified in the relevant manufacturer's certificate or Minister's approval certificate in accordance with regulations under section 48(4) of this Act.
The Secretary of State may by regulations—
(a) exempt from all or any of the foregoing provisions of this section the use of goods vehicles for such purposes or in such an area as may be prescribed ;
(b) exempt any class of goods vehicles from the provisions of subsection (2) above ; and
(c) make provision for the issue in respect of a vehicle in such circumstances as may be prescribed of a certificate of temporary exemption exempting that vehicle from the provisions of subsection (1) above for such period as may be specified in the certificate.