[1][2] The couple married in 1918, and when Keane revived Romance in New York City in 1921, Sydney made his Broadway debut in the parts.

[3][4] He stayed in New York for over a decade playing a variety of roles such as Mercutio in Romeo and Juliet (1922), Domin in R.U.R.

(1922), Richard Dudgeon in The Devil's Disciple (1923), the title role in Hamlet (1923), Prince Hal in Henry IV, Part I (1926), and Petruchio in Taming of the Shrew (1927).

[6] He made over 50 screen appearances, most memorably as Claudius in Laurence Olivier's 1948 film of Hamlet.

[7] He also appeared in classic films like Treasure Island (1950), Ivanhoe (1952), and Around the World in Eighty Days (1956), but the focus of his career was the stage on both sides of the Atlantic.