Bancroft was born in Rotherhithe, London. His first appearance on the stage was in 1861 at Birmingham, and he played in the provinces with success for several years. His first London appearance was in 1865 as Jack Crawley in J. P. Wooler's "A Winning Hazard" at the Prince of Wales's Theatre off Tottenham Court Road. He was then using the stage name Sydney Bancroft; also in the cast was his future wife, Effie Wilton. This theatre was managed by Henry Byron and Wilton, whom Bancroft married in December 1867. After their marriage the Bancrofts became joint managers of the theatre.