She relocated to London at the age of four after her parents separated, where she went on to study art history at Goldsmith's College. She got her start as an actress as a member of the Royal Court's young theater group, eventually landing roles in the films Winter Passing, Aeon Flux, and Stoned, as well as the 2000 BBC adaptation of Lorna Doone. In 2009, Warner launched her music career by composing the song "Beasts" (under the moniker Slow Moving Millie) for a television commercial, which went on to be released as a single. She inked a deal with Island Records in 2011 and released her first studio album, Renditions, which featured two original cuts ("Beasts" and "Hart with a Crown and Chain"), along with eight ballad-style covers of classic cuts from the '80s, including versions of "Head over Heels" (Tears for Fears), "Hold Me Now" (the Thompson Twins), and the Smiths' "Please Please Please Let Me Get What I Want," the latter of which found success after being chosen to appear in the 2011 holiday advert for the popular U.K. department store chain, John Lewis. ~ James Christopher Monger