Shelley's early career included roles in British films such as "It's Great to Be Young" (1956), "Carry On Regardless" (1961), "No My Darling Daughter" (1961), "The Cool Mikado" (1962) and "Carry On Cabby" (1963). In 1968 Shelley starred as Gwendolyn Pigeon in the film "The Odd Couple". Thereafter she took on numerous roles in television and films such as "The Boston Strangler" (1968), "Some Kind of a Nut" (1969), "The Whoopee Boys" (1986), "Little Noises" (1992), "The Road to Wellville" (1994), and she played Helen Moskowitz in the Emmy-winning 1998 "Frasier" episode "Merry Christmas, Mrs. Moskowitz".