I have just been done for speeding, I was overtaking a vehicle doing approx 20 mph on a straight piece of road, whilst overtaking safely I obviously went over the speed limit and as I did this a mobile speed camera up the road zapped me. Now after I passed the slower vehicle I slowed down to a normal speed. Are speed cameras supposed to take an average speed and are you allowed to exceed the speed limit for a short distance to overtake slower vehicles.