8.—(1) This regulation applies to works trucks, road rollers and agricultural machines.
(2) A registration plate must be fixed on the vehicle in a vertical position or, where that is not possible, in a position as close to the vertical as is reasonably practicable—
(a)on both sides of the vehicles, so that the characters of the mark are easily distinguishable from both sides of the vehicle, or
(b)on the rear of the vehicle, so that the characters of the mark are easily distinguishable from behind the vehicle, or
(c)where the vehicle is towing a trailer or trailers and the plate is not fixed on the sides of the vehicle, on the trailer or the rearmost trailer (as the case may be) so that the characters of the mark are easily distinguishable from behind the trailer.
(3) Where the towing vehicle is an agricultural machine, a plate fixed on the trailer may, instead of displaying the registration mark of the towing vehicle, display the mark of any other agricultural machine kept by the keeper of the towing vehicle.