Ellison had a run in the London West End theatre version of the musical Chicago in 2004 at the Adelphi Theatre, and returned from 10 July to 9 August 2006 again playing the leading role of "Roxie Hart", this time at the Cambridge Theatre. Ellison was actually supposed to finish on 12 August, but was forced to pull out three days early due to a knee injury. Ellison subsequently toured England in Chicago from 25 September 2006 until 5 May 2007, appearing in Birmingham, Manchester, Sunderland , Nottingham, Southampton, Stoke-on-Trent and Liverpool . On 1 October 2007, Ellison joined the cast of a revival of Boeing Boeing at the Comedy Theatre, London, playing the part of Gloria, an American TWA air stewardess. On 5 December, she featured in a 10th Anniversary Gala performance of Chicago at the Cambridge Theatre alongside a galaxy of stars and on 16 December, she will play "Angel" in Liverpool Nativity, a contemporary retelling of the Christmas story for BBC Three which will be performed live from the streets of the City. 
