[2] 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 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.

[4] They again performed the two plays in repertory at the New London Theatre on Drury Lane,[5][6] opening in November 2007 and closing mid-January 2008.

After the Scottish National Party won 56 seats at the 2015 general election, she caused controversy after making comments on Twitter comparing the SNP to the Third Reich, further stating "God help us all is all I can say when the racist S.N.P.

[15] In 2018, she was among the signatories to a letter published in The Observer arguing that debate surrounding reforms of the Gender Recognition Act were being silenced.