In high school one of my classmates did a study abroad program in Australia for half our senior year. When she returned, she gave a speech and suddenly had this Aussie accent (a poorly done Aussie accent, may I add).
I moved to the Philadelphia area 10 years ago, and often times when I meet a new person they ask me where I'm from, since I don't have to Philadelphia "accent"...yes, I say "water" not "wood-er" :) so I find it hard to believe this British accent thing is real.