Barber was born in
Wolverhampton, Staffordshire. Her parents are S.W. Brookes and Gladys Simpson; Barber is the fourth of six children. She attended the
Wolverhampton Municipal Grammar School. Barber studied drama at the
University College of North Wales in
Bangor, where she was a contemporary of director
Danny Boyle, who became her boyfriend. She appeared in the
Pet Shop Boys' musical
Closer to Heaven in 2001 as well as being guest singer for the song "Friendly Fire" on the Pet Shop Boys' 2006 live concert at the
Mermaid Theatre. She also appeared alongside
Ian McKellen and
Roger Allam in the Old Vic's
pantomime production of
Aladdin in the 2005–2006 Christmas season. She again starred with Ian McKellen in 2007 playing Goneril in
Trevor Nunn's production of
King Lear and as Arkadina in
Chekhov's The Seagull with the
Royal Shakespeare Company in
Stratford-upon-Avon followed by a world tour throughout the year. They again performed the two plays in repertory at the
New London Theatre on
Drury Lane, opening in November 2007 and closing mid-January 2008. In 2011, Barber guest-starred in the
Doctor Who episodes "
A Good Man Goes to War" and "
The Wedding of River Song" (and five other episodes, sometimes uncredited) as Madame Kovarian. She also acted in the television film ''
We'll Take Manhattan'' as
Diana Vreeland. In 2019, she starred in the Pet Shop Boys' musical
Musik. In May 2022, Barber appeared as Lesley in series 8 episode 4 of BBC dark comedy series,
Inside No. 9 (2022), in the episode titled "Love Is a Stranger". ==Political views==