[jambutty]

Sorry katex but your interpretation of the meaning of green is erroneous.

Taken from http://www.highwaycode.gov.uk/signs01.htm
RED - means 'Stop'. Wait behind the stop line on the carriageway.
RED & AMBER - also means 'Stop'. Do not pass through or start until GREEN shows.
GREEN - means you may go on if the way is clear. Take special care if you intend to turn left or right and give way to pedestrians who are crossing.
AMBER - means 'Stop' at the stopline. You may go on only if the AMBER appears after you have crossed the stop line or are so close to it that to pull up might cause an accident.
A GREEN ARROW - may be provided in addition to the full green signal if movement in a certain direction is allowed before or after the full green phase. If the way is clear you may go but only in the direction shown by the arrow. You may do this whatever other lights may be showing. White light signals may be provided for trams.