Highway Code Rule 178

Advanced stop lines. Some signal-controlled junctions have advanced stop lines to allow cycles to be positioned ahead of other traffic. Motorists, including motorcyclists, MUST stop at the first white line reached if the lights are amber or red and should avoid blocking the way or encroaching on the marked area at other times, e.g. if the junction ahead is blocked. If your vehicle has proceeded over the first white line at the time that the signal goes red, you MUST stop at the second white line, even if your vehicle is in the marked area. Allow cyclists time and space to move off when the green signal shows.

Laws

Rule 178: Do not unnecessarily encroach on the cyclists waiting area
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