Offbeat, petite, uniquely plummy-voiced leading lady who graced several classic British comedies of the 1940s and 50s, including "Kind Hearts and Coronets" (1949), "The Man in the White Suit" (1951) and the screen version of Oscar Wilde's "The Importance of Being Earnest" (1952). The gifted Greenwood possessed a special blend of the aristocratic and the sultry which made her extremely useful for a time in British film; later she specialized in highly enjoyable character roles, still classy and authoritative but more eccentric than sexy, in films including "Mysterious Island" (1961) and "Tom