I used to bump into famouses (plural of famous people) All The Time when I lived in London.
We lived practically next door to: Damian Lewis (tall, gorgeous kids), Charlie Higson (totally unstarry), Neil Kinnock (jumping out of a taxi), Sarah Cawood (small, pretty), Jenny Frost (small, pretty), Roland Gift (we terrorised him, oops) and loads more.
We also used to bump into famous people out and about in Camden. I DJed at a party for Matt Smith (seemed nice), saw Amy Winehouse out and about (small, beautiful), and used to see various comedians and band members (Graham Coxon is gorgeous btw).
My OH used to work in a record store in central London and threw Liam Gallagher out for smoking a fag in there. He was really nice and apologetic!