In addition to conducting and music directing the original productions of several of the most famous Gilbert and Sullivan works and writing the overtures to some of them, Cellier conducted at many theatres in London, New York and on tour in Britain, America and Australia. He composed over a dozen operas and other works for the theatre, as well as for orchestra, but his 1886 comic opera, "Dorothy", was by far his most successful work. It became the longest-running piece of musical theatre in the nineteenth century.