[2] A heavily built man with a striking double-chin and a deep voice, Sullivan made his acting debut at the Old Vic at age 18 in Shakespeare's Richard III.

He had considerable theatrical experience before he appeared in his first film in 1932, The Missing Rembrandt, as a German villain opposite Arthur Wontner as Sherlock Holmes.

He appeared in a fourth Dickens film, the 1935 Universal Pictures version of The Mystery of Edwin Drood, in which he played Crisparkle.

In 1938 he starred in a revival of the Stokes brothers' play Oscar Wilde at London's Arts Theatre.

[4] Sullivan, who became a naturalised American citizen on 27 December 1954, won a Tony Award in 1955 for the Agatha Christie play Witness for the Prosecution.