Sam put on a very convincing Southern accent for Nashville and told Elle magazine it was thanks to the "great training" he had — including all the accent work he did at drama school. He credits having "a musician's ear for listening" and likes to listen to conversations in bars to pick up accents.
That came in handy when he was at the read-through for the movie Runner, Runner, as he was asked to read all of the other bit parts. By reading seven different parts with all the different accents, he managed to impress a couple of people in the room.
He told Digital Spy he's determined to keep his English accent intact, though, saying that as soon as they say "cut", he's back in his hometown voice. He's met a lot of English people in the US whose voices are turning very American, but he wants to retain his accent and "keep it where it belongs!"