Cox and Box, also known as The Long-Lost Brothers, is a one-act comic opera with a libretto by F. C. Burnand and music by Arthur Sullivan, based on the 1847 farce Box and Cox by John Maddison Morton. It premiered in 1866 and was Sullivan's first successful comic opera. The story concerns a landlord who lets a room to two lodgers, one who works at night and one who works during the day. When one of them has the day off, they meet each other in the room and tempers flare. Sullivan wrote this piece five years before Thespis, his first opera with W. S. Gilbert. This poster was produced for the first professional production of Cox and Box, which began in 1869 at the Royal Gallery of Illustration in London and ran for 264 performances there. The opera has frequently been used as a curtain raiser for the shorter Gilbert and Sullivan operas and continues to be frequently produced.Poster credit: Alfred Concanen; restored by Adam Cuerden