https://www.confused.com/on-the-road...era-tolerances
I heard rumours that the newer ones that sit by the side of the smart motorways have very tight tolerances. Not sure how true this is.
I noticed down in Dorset the other week that lots of old GATSO cameras that had stood mostly empty for years had all been upgraded to newer cameras.
My mother got sent on a speed awareness course by the local police because she was pulled up for doing 40mph on a country road where the speed limit was 60mph. She said she had turned onto the road and was only doing a very short section of the road before turning off so she didn't want to have to speed up to the maximum. Copper still issued a NiP and made her do a speed awareness course where they lectured her on the evils of driving too fast.