Brook was born and died in London. Brook was 5 ft 11 in (1.80 m) tall and had brown hair with grey eyes. He was the son of an opera singer, a published writer and a violinist. He was educated at Dulwich College and served as an officer in the Artists' Rifles in the First World War. He first appeared on stage in 1918 and also in films from 1919. He worked first in British films then in Hollywood.
One of his best remembered appearances was playing opposite Marlene Dietrich in Shanghai Express (1932). He played Sherlock Holmes three times: The Return of Sherlock Holmes and Sherlock Holmes (in that order), and as part of an anthology film, Paramount on Parade (1930). In 1934 he was voted one of the most popular stars at the British box office.
Return to Britain
In 1943, he adapted the comedy On Approval by Frederick Lonsdale and wrote, produced, directed and starred in the film with Beatrice Lillie, Googie Withers, and Roland Culver. The costumes were by Cecil Beaton. In 1949 he presented the radio series The Secrets of Scotland Yard. In 1956 he appeared on stage in One Bright Day at the Apollo Theatre in London.
Brook married Mildred Evelyn, and their daughter, Faith Brook was an actor as was their late son, Lyndon Brook.