12.—(1) The Department authorises the use on roads, notwithstanding that such vehicles do not comply with the requirements of regulation 7 of the Construction and Use Regulations, of an agricultural motor vehicle towing an agricultural trailer or agricultural trailed appliance in such a manner that the longitudinal axis of the motor vehicle and the longitudinal axis of the trailer are parallel but lie in different vertical planes and the width specified in paragraph (2) exceeds 2.55 metres provided the relevant conditions specified in Schedule 2 are complied with.
(2) The width referred to in paragraph (1) is the distance equivalent to the distance which, if both the agricultural motor vehicle and the agricultural trailer or agricultural trailed appliance (when being drawn by the agricultural motor vehicle) are treated as one vehicle, would fall to be measured as its overall width.