There is a regular place
here that they sit at with a camera van facing down the hill. However, you can see the van from the bottom of the dip and all of the opposing cars flash their headlights (because the van cannot see them). The speed limit down there is 30 however people always go over it (I have had people overtake me when I am doing 30 down there).
I always read in the newspaper about the campaigns that the police have and all the people they catch. So although they might be few and far between, they do catch people when they are out.