He is known for his dubbing work in the James Bond film series, Lawrence of Arabia, Once Upon a Time in America, and The Guns of Navarone.

In 1932, at the age of nine, he joined his father's company Teatro Italiano, making his stage debut in Mysterious Currents.

Despite letting down Alfred Hitchcock, who handpicked him to play the lead in Sabotage (1936), he made 17 motion pictures during the 1930s, remaining a popular child actor throughout that decade.

[4] He later joined the Rifle Brigade, but accepted the army's request for him to head "Stars in Battledress", a group of young actors, which included the young Peter Ustinov and Terry-Thomas, who toured England, and were flown throughout liberated Europe, to entertain Allied troops.

After the war, he returned to work in the theatre, films, radio, and the latest medium, early television.

He was also a regular on the radio series Horatio Hornblower (1952) with Michael Redgrave, The Scarlet Pimpernel (1952), Theatre Royal (1954) with Sir Laurence Olivier, and the classic Sherlock Holmes (1954) with John Gielgud and Ralph Richardson.

He guest starred together with his father in The Jack Benny Program (1957) and in Harry's Girls (1960), which were both directed by his friend Ralph Levy, director of The Burns and Allen Show.

Among the earliest of his film appearances were with Leslie Howard in The Scarlet Pimpernel and with Douglas Fairbanks in The Private Life of Don Juan (both 1934).

His own voice was used to re-voice Gregory Peck's German dialogue in The Guns of Navarone (1961); and Orson Welles' in Treasure Island (1972).

He founded and served as executive editor for 18 years of Gambit, a theatre quarterly which published international plays, including many of his own.