Best known for his talent for ballet, he was one of the three boys who shared the lead role in the original London cast of Billy Elliot the Musical which earned a Laurence Olivier Award for Best Actor in a Leading Role in a Musical, making him the youngest nominee and the youngest solo winner in the category aged 13.

He became a boarding pupil at the Royal Ballet School (RBS) whilst still auditioning for Billy Elliot, but later scaled down his connection to it, in order to be able to meet his professional commitments without losing out on quality of life.

[2][3] Mower also attended the Northern Academy of Performing Arts (NAPA) in Kingston upon Hull,[4] but now studies at the Rambert School of Ballet and Contemporary Dance in Twickenham.

[7][8][9] Upon his departure, Stephen Daldry stated that "Liam is a unique talent and we have all been blessed with the opportunity to see him flourish in Billy Elliot over the past eighteen months.

[5] He did very well at his GCSEs with 14 grades from A* to C.[13] Mower also previously stated that he would like to be a dancer before being an actor: "After I have got my degree at the school I would like to join a dance company and then go into acting a bit later.

In the interview, Billy Elliot lyricist Lee Hall said that on the first run through of the show, Mower was so physically strained that he vomited at the side of the stage after performing Angry Dance.

[16] From December 2014 - January 2015, Mower starred in Matthew Bourne's New Adventures production of Edward Scissorhands at Sadler's Wells in London.

He won, jointly with James Lomas and George Maguire, the 2005 Theatre Goers' Choice Award for The Most Promising Newcomer.