New Traffic Signs Regulations and General Directions came into force in April 2016 and, although the requirement for sign illumination has been relaxed in many cases, certain signs require direct illumination if they are within 50 metres of a street lighting system.
The exception is where the signs are mounted within a 20mph zone, where all but a couple of signs are not required to be illuminated. Signs which are not illuminated should be reflectorised.
Where a sign needs to be directly lit, but street lighting is turned off during part of the hours of darkness, the sign must also be reflectorised unless the sign remains. Generally, warning signs (triangular signs) no longer need to be illuminated with the exceptions of some safety critical signs.