sentences:  Thornton began his stage career giving drawing-room entertainments while simultaneously working in a commercial office in London, keeping his theatrical activities secret from his office employers for four years.He was engaged by Richard D'Oyly Carte as understudy to George Grossmith in the Gilbert and Sullivan operas, also playing roles in some of the curtain raisers played with the operas.In 1881, he created a small principal role in "Patience" and resigned from his office post.