Although Gilbert announced a retirement from the theatre after the short run of his last work with Sullivan, "The Grand Duke" (1896) and the poor reception of his 1897 play "The Fortune Hunter", he produced at least three more plays over the last dozen years of his life, including an unsuccessful opera, "Fallen Fairies" (1909), with Edward German. Gilbert also continued to supervise the various revivals of his works by the D'Oyly Carte Opera Company, including its London Repertory seasons in 1906–09. His last play, "The Hooligan", produced just four months before his death, is a study of a young condemned thug in a prison cell. Gilbert shows sympathy for his protagonist, the son of a thief who, brought up among thieves, kills his girlfriend. As in some earlier work, the playwright displays "his conviction that nurture rather than nature often accounted for criminal behaviour". The grim and powerful piece became one of Gilbert's most successful serious dramas, and experts conclude that, in those last months of Gilbert's life, he was developing a new style, a "mixture of irony, of social theme, and of grubby realism," to replace the old "Gilbertianism" of which he had grown weary. In these last years, Gilbert also wrote children's book versions of "H.M.S. Pinafore" and "The Mikado" giving, in some cases, backstory that is not found in the librettos.