This is information for drivers in the London area
From the 15th February 08 all the Speed Cameras in the Variable Speed Limit section of the M25 near Heathrow Airport (JCT 10-15) are going Digital and the activation limit is being lowered.
They are currently the older film type cameras and set at 90mph when the Variable Limit Signs are not in operation.
The new digital cameras are going to be set at the normal 10% of the speed limit + 2mph (80mph + and youre taking a risk basically) when the signs are not in use i.e. national speed limit. I cant confirm the activation limit when the signs are set (variable limits showing) but believe it would be the same 10% + 2mph of the speed shown by the sign at that time.
I hope this saves a few of you getting points on your licence!!!