There are over 1,000 red light camera locations in the UK. These cameras are designed to flash if the motorist has jumped a red light. This usually occurs when the lights turn steady amber but the motorist continues when he could have stopped. This is happens either because the motorist was not paying attention to the lights, or more likely, is in a hurry and doesn't want to stop.
The sequence of the traffic lights is RED - stop, RED & AMBER - stop, GREEN - go if it safe to do so, AMBER - stop, RED - stop. You may only continue on steady amber if you have already crossed the stop line or to do so would cause an accident.
If you get caught by a traffic light camera, the normal fine is £60 with 3 points on your licence.