What do David Cameron, Ming Campbell and I have in common?
[prepares himself for an onslaught]
UPDATE:Some hilarious suggestions so far - some even true, but not the one I'm looking for.
UPDATE Thur 9am: Daily Referendum got closest. The answer is that David Cameron, Ming Campbell and I all go to the same dental practice. You really did come up with some hilarious answers though. And some highly insulting ones too!