well, funny though. I sent an email to the police and the replied sounded like this
thank you for your email dated 1 August 2003.
In answer to your questions, if your vehicle is not exceeding the posted
speed limit the vehicle can not be recorded by a speed camera.
The speed camera can ID which vehicle in a photo has exceeded the speed
limit.
I hope this information helps
Yours sincerely
XXXXXXXX
Acting Sergeant
Traffic Camera Section """"