Washbourne was performing professionally from the early 1920s. She married the actor Basil Dignam. Her brother-in-law Mark Dignam was also a stage and film actor. In 1948, after numerous stage musical performances, Washbourne began appearing in films. Her film credits include the horror movie The Brides of Dracula, Billy Liar (1963) and The Collector (1965). She played Mrs. Pearce in My Fair Lady (1964), the stern and caustic Mrs. Bramson in the remake of Night Must Fall (also 1964), and the Matron in the film, If.... (1968).