Most notably, Barker played Ilse in the original London cast of the four-time Olivier Award-winning Spring Awakening which opened in February 2009 at the Lyric Hammersmith.

Also in 2010, in the season at the Open Air Theatre, Regent's Park, Barker played Mercy Lewis in The Crucible, starring alongside Oliver Ford Davies, Emma Cunniffe, Susan Engel and Patrick Godfrey.

[7] In late 2010, Barker filmed a small role in The Woman in Black, starring Daniel Radcliffe, and was also seen on CBBC's show Scoop, with Shaun Williamson and Mark Benton, in early 2011.

[8] At the start of 2011, Barker toured the UK playing Clarissa in The Reluctant Debutante, with Jane Asher, Clive Francis and Belinda Lang.

In 2019, she returned to Mamma Mia as Sophie, this time at the West End's Novello Theatre, replacing Georgia Louise who departed the cast prematurely due to illness.