Mitchell won the Worshipful Company of Musicians Maisie Lewis Young Artist Award in 1984, resulting in her debut at the Purcell Room at London's South Bank Centre, with further recitals there as Park Lane Group Young Artist 1985 and as winner of the Kirckman Concert Society recital award 1986, when she commissioned her first work, Fantasia by Brian Elias. Mitchell served from 1985-1987 as the violinist/violist member of Peter Maxwell Davies's performing group, The Fires of London. In 1992, she was a member of the Michael Nyman Band; she performed on the recording "The Michael Nyman Songbook" and appeared in Volker Schlöndorff's concert film.