Bang To Rights

I was pulled up for speeding locally by one of the unmarked cars a few weeks back. I was on something of a mercy mission and simply had my eyes off the ball, not thinking about the 30 limit. I can't complain, and am very disappointed in myself. I take speed limits as seriously as any other aspect of the laws of our land and normally keep firmly to them - not least because I've seen what speed does to people - drivers, passengers, pedestrians - when there are accidents. But I would just want to say that there have been several occasions since then when I have observed marked and unmarked police vehicles exceeding speed limits. No problem when the blue light is flashing and there's an emergency to attend - but surely at other times the police should be subject to the same rules of the road as everyone else, and indeed should be setting an example to others?