Howard, I got caught last week by a speed camera in a lay by on the A64 approaching Malton from York,at 0620, the road changes from a dual carriage way to single road which I assumed (wrongly) to be 60mph, It turns out that it was 50mph and I was clocked at 57mph.
Four days later a letter came asking who was the driver (my wife refused to take one for the team) it stated that North Yorkshire Police have a policy of only prosecuting at 10%+2mph which in my case is 57mph so it is a bad boys course for me I suppose.

David Byrne