Position of traffic signal cameras - narbz
Today as I was driving to work I passed the stop line at a junction just as the lights were changing to amber; they changed to red as I was about halfway through the junction. At this point I noticed a flash from a pole mounted camera in between the two carriageways. (through my front windscreen, on the right). On later inspection I found that the camera appears to be angled towards the other side of the road (i.e. towards the oncoming traffic as I was going through the junction) and would have been taking photos of the back of oncoming vehicles.

I may be being paranoid but I'm not very familiar with traffic signal cameras - are they normally positioned so that they take a photo of the back of your car? And if it was a speed camera as well would that be the same? I'm wondering whether this camera flashed because it caught someone going the other way running a light...
Position of traffic signal cameras - Rattle
If you passed the white line on amber or green you won't get a ticket, the flash was for the car behind or the signals in the opposite direction.
Position of traffic signal cameras - Pugugly
If you do a forum search there was a wide ranging debate about these when a member thought he'd been flashed by a camera. May be helpful.