Mantle has worked extensively on the stage in such productions as "My Fair Lady", "Keep It in the Family", "The Seagull" and "Hamlet". She also toured Britain in "Billy Liar" in the role of Florence Boothroyd and performed at the National Theatre in "The Voysey Inheritance". In 1979 she was awarded the Laurence Olivier Award for Best Actress in a Supporting Role for her performance in "Death of a Salesman". She has also done a great deal of radio work for BBC Radio 3 and BBC World Service. Mantle played the long suffering wife of the rabbi in BBC Radio 4's comedy series "The Attractive Young Rabbi".