Road sign

A road sign 10 comprising a light sensor 18 for detecting light from vehicle headlights or headlamps, such as a car, lorry or a horse and rider, and a signal assembly 14 comprising a display device 16 which is operable on detection of vehicle headlights by the light sensor. A solar panel 22 may be used to power the display device. There may be multiple display devices or signal assemblies which are activated by more than one light sensor. The system may be activated when ambient atmospheric conditions, e.g. darkness, is detected, or at specific times of day or night. Shielding may be provided around the sensor to limit the direction. The sign may be controlled remotely. The road sign is preferably located near tight bends in the road or other dangerous areas such that it detects approaching traffic and lights up as a warning. A kit of parts for mounting to a sign is also provided.