It is a legal requirement for motorists to ensure that their sidelights to also include the rear registration number plate are illuminated between sunset and sunrise. Sidelights must also be used during the hours of daylight when visibility is reduced.
The law also states that drivers must park their vehicle at night facing the direction of the traffic flow unless in a recognised parking space and to use sidelights or parking lights if parked on a road with a speed limit greater than 30mph.
Admittedly i picked two of the least abided by parts of the law…. what part was it you specifically wanted to know.
oh and its RTC in 2014