Yes sometimes they do and if anyone is working on the roads, then throw the book at the idiot. However a previous poster alluded to the section of road he was caught at and there appears to be no work being carried out and it sounds like the council are using it for a cash cow.
I do a lot of miles up and down the country and a lot of the time wonder what a certain speed restriction was for. It's either lazy signage or a money spinner when the council needs a new bus lane.