As well as acting he became tenant and manager of the Criterion Theatre and wrote many plays as well as adaptations of his own and others’ novels. In his later years he wrote and adapted for the screen. Amongst his notable works were Israel Rank: The Autobiography of a Criminal (1907), which was republished by Faber Finds in 2008 and again by Cavalier Classics in 2014.
The 1949 film Kind Hearts and Coronets was based on Israel Rank: The Autobiography of a Criminal and the novel also inspired the 2013 Broadway musical A Gentleman"s Guide to Love and Murder.
Horniman also wrote The Sin of Atlantis in 1900 and Lord Cammarleigh’s Secret: A Fairy Story of To-Day in 1907. Roy Horniman served in the Artists Rifles during the First World War.