Warner began her music career in July 2009, when she wrote and performed the song "Beasts" under the name Slow Moving Millie for a
Virgin Media television commercial. The track was then released on 17 August 2009. Her second single, "Rewind City" was also used for another advertisement, for
Orange UK, and was directed by
Ringan Ledwidge. In October 2011, Warner signed a record deal with
Island Records. Her cover version of
the Smiths' 1984 B-Side "
Please, Please, Please, Let Me Get What I Want" was released on 11 November 2011 and was selected as the soundtrack to the
John Lewis 2011 Christmas advertisement. Since releasing her album,
Renditions, she also composed music for adverts and short films. Her first major score was for the British short,
Mam. Soon after, Warner released her
Fyfe Dangerfield-produced EP,
Arms, under Universal Music. Her second EP,
Visitors. In 2016, she scored her first feature-length film, ''Mum's List
, followed by her score to the film Mary Shelley''. ==Personal life==