[jeff st4s]

My mate worked in a police station (not one of the boys though).
He said that the standard yellow machines only get you from behind that is why they swivel around, the blue ones can get you front on.
It happened to me before I was going forwards towards a yellow camera in a car above the speed limit and it flashed at me, nothing arrived in the post.
He reckons it could simply be something small flew/blew in front of the lense and this set it off.
I was also told you sometimes see cameras double flash, this is them recalibrating themselves (a magistrate this time).