Grossmith had hoped to become a barrister. Instead, he worked for many years, beginning in the 1860s, training and then substituting for his father as the Bow Street reporter for "The Times", among other publications, when his father was on his lecture tours. Among the cases on which he reported was the Clerkenwell bombing by the Fenians in 1867. At the same time as he began reporting, he began to write humorous articles for periodicals and to participate in amateur theatrical performances. He also joined his father in his entertainments, lectures, and imitations, and began to add music to the entertainments, which his father had not done. In 1873, Grossmith married Emmeline Rosa Noyce (1849–1905), the daughter of a neighbourhood physician, whom he had met years earlier at a children's party. The couple had four children: George, Sylvia (1875–1932; married Stuart James Bevan in 1900), Lawrence and Cordelia Rosa (1879–1943). The family lived initially in Marylebone before moving, about 1885, to Dorset Square nearby.