Beginning his career in operetta, Leslie became best known for starring in, and writing (under the pseudonym A. C. Torr, a pun on the word "actor"), popular burlesque plays and other comic works of theatre.
[4] He soon appeared in operettas such as Madame Favart, La fille du tambour-major (1880)[5] and Olivette;[3] and he played Faust in Mefistofele (1880) with Constance Loseby as Marguerite and Lionel Brough as Valentine.
[4] In 1882, Leslie found wide success as the title character in the operetta Rip Van Winkle, by Robert Planquette, at the Comedy Theatre, also starring W. S.
The same year, at the Comedy Theatre, he played in H. B. Farnie and Edmond Audran's adaptation, The Great Mogul with Florence St. John, Frank Wyatt and Arthur Roberts.
In 1888–89, Leslie, with Farren's Gaiety company, toured in the US and Australia, in Monte Cristo Jr. and Miss Esmeralda (together with Sylvia Grey, Marion Hood and Letty Lind).
[15] In 1891, Leslie and Farren again toured Australia with the Gaiety company in Ruy Blas and Cinder Ellen up too Late (with Sidney Jones as conductor).
[9] His early death, coupled with Farren's illness and retirement in 1892, brought to an end the type of Gaiety burlesque associated with them, at the same time that Edwardian musical comedy came to dominate the London theatre.