I got one just as they bought the 20 limit in for Tower bridge. I expect it was a highly profitable day. Despite the huge signs they had placed.
I got a second one a few years later on the dual carriageway out of Basingrad. It is a clear and usually commuter fast 50.In both cases I was less than 10% over the limit but still over it.
Comparing the two it seems like all good floor shows, it depends in part on the audience participation.
London was denial based non-participation. Boring course with a load of complaining about waste of tax payers money. They actually had all the local figures for the area and it made more sense because of it.
Basingrad was funny. There are loads of boy racers in the area and several of the inmates were of the souped up Corsa brigade. They did engage (I will admit to coaxing them on a bit with jokes about furry dice being non-aerodynamic and excessive weight in an 80hp Corsa/Fiesta) and it was actually pretty good with most people seeming to admit to reconsidering their actions.
I consider them a good thing - no points, no fines, no insurance issues. Just leaves a three month telling off from the missus to deal with, do you think they could do something about that?
I will admit that turning up to the second one in a 600hp RS6 was probably not good as they apparently watch who/what arrives and base the training on it! I believe I got more than my fair share of stick