British actors with American accent on tv and screen

It's common to find British actors on American tv and screen. Many of them speak with a very good American accent that everyone thinks he/she was really born in US. In 2008, a poll conducted by the site Radio times showed that Hugh Laurie (House M.D.) has the most authentic American accent from TV. The first ones are:

1. Hugh Laurie (House)
2. Anna Friel (Pushing Daisies)
3. Michelle Ryan (Bionic Woman)
4. Damian Lewis (Band of Brothers)
5. Minnie Driver (The Riches)

Hear Hugh Laurie's American accent
Hear Hugh Laurie's British accent

And you? Agree with the survey?