after checking with the retained copper types who do our driving assesments:

there is not a set limit for amber/red changing as some will do it faster than others, but i think what jim is enquiring about is if there is a minimum time that the light MUST be amber for before it goes to red, but unfortunatly i cannot unearth this information at this present time

red light camera's do tend to be operational within the 2 seconds after the lights have turned red until they turn green again

how many pictures have been taken of the vehicle going through the light? if there are 2 then this will determine how fast it was traveling
if there is only one then you could argue that you were stationary or moving forwards very slowly, this would incuur a probabl £100 fine for being a twat, but no points

insurance companies frown on red light jumping more than they do for speeding offences and your license, if you are convicted of the offence, will reflect this by the penalty code

as a general rule though, the lights will stay amber for long enough so that anyone approaching the lights will have time to slow down and stop in time for the reds or carry n at the speed limit and not get caught by the camera

this is on the basis that you are maintaining the correct speed and not going faster than the posted limits

all this may be taken into consideration

your only mitigating circumstances wold be that you went through the lights as you did not want to cause an accident because the vehicle behind you was very close and, if you were to have stamped on your brakes, they would have collided with you

but if there is no second vehicle in the pcituer, then you can't use that arguement