Met McFly back in about 2004, so they must have been about 17 or 18ish? Really nice guys, very friendly. As were the boys from D-Side, another pop band from back then.
A mention for Jimmy Carr also. Didn't actually meet him, but went to see him on Saturday and he stayed behind after the gig to go out into the foyer, do signings and have some drinks. My brother says he generally does it, and he came across as a very nice guy.