A leading man, he became well known for his stage interpretation of Sherlock Holmes, was an early mentor of Charlie Chaplin, and is considered an authority on the work of Sir Henry Irving.

His father had married Sarah Charlotte, second daughter of Robert Lemon, FSA, of Her Majesty's State Paper Office, at St Luke's Church, Chelsea, on 13 October 1854.

[6] In March, 1887, Saintsbury made his first appearance on stage at the Opera Comique Theatre as a super in Kate Vaughan's revival of Reade and Taylor's Masks and Faces.

Those produced include Betrayed by a Kiss (1891), The Friend of the People (1893), The Doctor's Shadow (1896), His Relations (1896), The Eleventh Hour (1896, in collaboration with Ronald MacDonald), The Three Musketeers (1898), Chicot the Jester (1898), The First Night (1899), Don Caesar de Bazan (1899), and Jim: a Romance of Cockayne (1903).

From the middle of June 1901 he was at the new theatre as leading man for ten weeks, playing flamboyantly in costume dramas such as Jane Shore, David Garrick, and his own Don Cesar de Bazan.

[10] Charles Millward took over the role when the production moved to New York, but Saintsbury returned as Holmes in a West End revival of the play in 1921.

[11] Saintsbury played the role of Holmes again in a 1916 film, The Valley of Fear, which is believed lost, opposite Booth Conway as Professor Moriarty.

[21] Saintsbury died at St Thomas's Hospital, Westminster, on 19 June 1939, when his home address was 88 Woodstock Road, Bedford Park, leaving an estate valued at £544.