I take it they don't flash ?

Dozey from jetlag, coming back from work, 73 in a 50 limit in a non familiar car ( I think)

I have been told they do give a bright red flash so it sounds like you are lucky.

Still checking the post box every morning !!

Possibly this type of camera

"Truvelo Speed Cameras
The forward facing Truvelo camera system is designed to take photographs of the front of a passing vehicle. This allows the picture taken to show the driver of the vehicle as well. In countries such as Switzerland, Germany and the Scandinavian countries driver recognition is a required factor to enable a successful prosecution of a speed or red light offence.

A single front photograph, taken just after the vehicle has crossed the piezo sensors used for speed measurement, includes all the secondary check information required.

To avoid the 'flash' which is given out by a rear facing Gatso camera the Truvelo system uses an infra red flash which produces no visible 'flash' to the approaching driver."

Sorry to report if this is true Colin.