Fun fact: American Southern accents are pretty easy for English actors to mimic. Because it's entirely possible that pre-American English accents were closer to modern Southern accents than to modern English accents.
Tom Hiddleston Shines as Hank Williams in I Saw The Light
“When people ask me, ‘Why’d you get an Englishman?’ I say, ‘He’s the best actor I know to play the part,’” Abraham says. “Who’s the most famous southerner ever portrayed in the movies? Scarlett O’Hara. Who plays her? Vivien Leigh.” [Marc Abraham. Source EW: Tom Hiddleston was the best choice to play Hank Williams in I Saw the Light http://www.ew.com/article/2015/08/17/tom-hiddleston-channels-hank-williams-i-saw-light]
Stills and behind the scenes images from I Saw the Light. (Via precurorpress.tumblr & Torrilla). Full size image: http://maryxglz.tumblr.com/post/161690113922/i-saw-the-light-2015-via-precursorpresstumblr