 Additionally, she appeared with Michael Winner in a British TV advert for Esure car insurance.She played Queen Margaret of Anjou in the BBC Television Shakespeare adaptations of "Henry VI, Part 1", "Henry VI, Part 2", and "The Tragedy of Richard III", which received its UK broadcast in January 1983.After her stage debut with the Brighton Repertory Theatre, Foster made her London debut in "Travelling Light" in 1965 at the Prince of Wales Theatre; she has since appeared in several London stage productions, including at The Globe Theatre, Lyric Theatre (Hammersmith), Queens Theatre, Criterion Theatre, King's Head Theatre, Royal Court Theatre, Apollo Theatre, New End Theatre, also in the UK at the Nottingham Playhouse, New Theatre, Oxford, Birmingham Repertory Company, and the Citizens Theatre, Glasgow.