Rule 176

You MUST NOT move forward over the white line when the red light is showing. Only go forward when the traffic lights are green if there is room for you to clear the junction safely or you are taking up a position to turn right. If the traffic lights are not working, treat the situation as you would an unmarked junction and proceed with great care.

Laws RTA 1988 sect 36 & TSRGD regs 10 & 36