I have driven through red lights at the request of the boys in blue a few times... It's always been from directions of a traffic officer standing, and in one case they were actually fiddling with the traffic light camera / testing it as everyone including myself was being flashed.

I would never take instructions from anyone inside their car - too much margin for error as they couldn't be seen properly ("sorry, I thought you meant it was OK to move forward into the path of the big lorry").

On the occasions where there has been an ambulance / whatever and I've been at the front of the queue, there is always plenty of room to move the car out of the way long before you hit the sensors on the road. There is a big difference between giving space to the vehicle behind to squeeze through and just driving forward as if the light was green.

If you suspect that a traffic light has failed on red, there's that period of time when you're weighing up whether or not the light has really failed and how long to wait before cautiously edging forward.

As an aside on failed lights, we had some roadworks near us where they installed temporary lights controlling a stretch of road that went round a bend. I drove through and it was apparent that cars coming the other way were ignoring the red light. But after getting home I walked back to the lights and I established that the lights were showing green simultaneously at both ends!