Cynthia is most famed for her roles in L.A. Law (1986), Edward & Mrs. Simpson (1978), Mad About You (1992). She made her Broadway debut in 1963. In 1971, she appeared on Broadway in the Landmark Stephen Sondheim-George Furth musical, "Company". She is a founding member and co-artistic director of The Actor's Company Theatre. In 1978, she received a BAFTA nomination for her performance as "Wallis Simpson" in Edward & Mrs. Simpson (1978).