More than 53 million people call England home, according to Britain's Office for National Statistics. That's certainly not a paltry number, but compared with the planet's 7 billion and counting ... well, it's a drop in the proverbial bucket. Nevertheless, British accents dominate the box office anytime someone needs to sound highbrow, royal, evil, intelligent or otherwise not American.
English accents occur regardless of the geographic location of the film. You'll even hear it in movies set in periods before England existed. "The Lord of the Rings" series? "Troy"? "Les Miz"? "300"? English accents were featured in all these movies. Perhaps it's because the dialect is pleasing (and understandable) to the American ear while still conveying the message that "this film is set in another place and time." Plus, an exotic accent totally ups the hotness factor of any actor.