Character of rear lamps
19.—(1)  Every rear lamp fitted on or to a vehicle shall, when lit, show a red diffused light to the rear of the vehicle.
(2)  The total rated wattage of the bulb or bulbs with which a rear lamp is fitted shall be not less than 5 watts or not more than 36 watts.
(3)  Notwithstanding paragraph (2), the total rated wattage of the bulb or bulbs with which a rear lamp is fitted shall be not less than 8 watts or not more than 36 watts in the case of either a public service vehicle adapted to carry more than 14 persons excluding the driver or a goods vehicle with an unladen weight exceeding 1,500 kilograms, if in either case the vehicle is registered on or after 1st July 1980.