Traffic lights at a junction in the City of London
Traffic lights system
When a GREEN signal is shown, it means that any vehicle may proceed beyond the stop line and proceed straight on or to the left or to the right, if it is safe to do so.
When an AMBER signal is shown, it means STOP. This is the same as for a red signal, except for when a vehicle is so close to the stop line that it cannot safely be stopped before the stop line, in which case it may continue as if a green light is shown.
When the traffic lights change to RED, all traffic must stop before the white stop line.
When the RED
signals are shown at the same time, this also means STOP. Do not pass through or start until the green signal shows.
Vehicles proceeding beyond a stop line in accordance with the above must proceed with due regard to the safety of other road users and subject to any direction given by a constable in uniform or a traffic warden or to any other applicable prohibition or restriction.
Road Traffic Act 1988, Section 36 & Traffic Signs Regulations and General Directions; Regulations 10 & 43(2)
If you fail to obey the traffic lights (as above), you are liable at the very least, to a £100 fine and your licence endorsed with 3 penalty points.