bill barlow is way off and he should appeal over his ticket!
Speed cameras work by taking two shots over a timed period. The distance travelled from the first flash (point a) to the second flash (point b) determines what speed you were doing.
If you are flashed from a camera on the other side of the road it is measuring the speed at point a but has not point b as reference.
You can only be judged (if you could- which you cant!) as doing a negative speed! There is nothing to worry about.
Saying all that the front facing Vito cameras are digital and infra red, take two shots over a matter of inches rather that feet and dont flash - so you dont even know youve been clocked. Plus they take a shot of you face so the authorities know who is driving.