Lisa Bowerman (born 1 February 1962) is a British actress. She is best known for portraying Sandra Mute, the paramedic, in the BBC One medical drama Casualty, in the first two series (1986–1987). She also stars as Doctor Who companion Professor Bernice Summerfield in a series of the same name and many Doctor Who audios for Big Finish Productions productions, as well as directing many series for the company. Source: Wikipedia (en)