Guys
After meeting with the 'Speed Camera Partnership' I can tell you 100% that you are wasting your money on these plates. They showed me pictures of these plates on cars taken by the cameras. The pics are over exposed but all they do is turn the pic to negative and the number is clearly readable.
A word of warning; the new digital cameras only flash in very low light levels so the plates would be useless anyway. Also the radar detectors you can buy do not pick up the digital cameras.
Also certain Boroughs are now trailing a new red light camera that also acts as a speed camera, so if you approach an amber light and put your foot down to beat the red light, you will trigger the camera and get a speeding penalty.
You are better off just driving sensibly and keeping your eyes open.
Sorry
Jason