On the whole, I think the UK controllers are excellent - helpful, patient and fair. I was once listening to what should have been a straight-forward and routine exchange between an ATC at Farnborough and the pilot of a Cessna something or other. The pilot was given a squawk no less than a dozen times, having failed to correctly read it back on each previous occasion. The controller, who must have been wondering what the hell the pilot was smoking, remained perfectly calm as he patiently repeated the 4 digit number ever more slowly, until the pilot finally got it...