thumb|300px|right|Poster for the 1869 production at the [[Royal Gallery of Illustration]]
Cox and Box; or, 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 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 his first opera with W. S. Gilbert, Thespis.
The piece premiered in 1866 and was seen a few times at charity benefits in 1867. Once given a professional production in 1869, it became popular, running for 264 performances and enjoying many revivals and further charity performances. During the 20th century, it was frequently played by the D'Oyly Carte Opera Company in an abridged version, as a curtain raiser for the shorter Gilbert and Sullivan operas. It has been played by numerous professional and amateur companies throughout the world and continues to be frequently produced.
Background
thumb|upright|left|Playbill from a New York production of [[Box and Cox (farce)|Box and Cox]]
The Moray Minstrels were an informal gathering of notable men involved in London society and the arts, including painters, actors and writers, who were mostly amateur musicians. They would meet for musical evenings at Moray Lodge, in Kensington, the home of Arthur James Lewis (1824–1901), a haberdasher and silk merchant (of the firm Lewis & Allenby), who married the actress Kate Terry in 1867. The Minstrels would discuss the arts, smoke and sing part-songs and other popular music at monthly gatherings of more than 150 lovers of the arts; their conductor was John Foster. Foster, as well as the dramatist F. C. Burnand and many other members were friendly with young Arthur Sullivan, who joined the group. On one occasion in early 1865, they heard a performance of Offenbach's short two-man operetta Les deux aveugles ("The Two Blind Men"). After seeing another operetta at Moray Lodge the following winter, Burnand asked Sullivan to collaborate on a new piece to be performed for the Minstrels.
Burnand adapted the libretto for this "triumviretta" from John Maddison Morton's famous farce, Box and Cox, which had premiered in London in 1847, starring J. B. Buckstone. The text follows Morton's play closely, differing in only two notable respects. First, in the play the protagonists lodge with Mrs Bouncer; in Burnand's version the character is Sergeant Bouncer. This change was necessitated by the intention of performing the piece for the all-male gathering of the Moray Minstrels. Secondly, Burnand wrote original lyrics to be set to music by the 24-year-old Sullivan. The date and venue of the first performance was much disputed, starting in 1890, in duelling letters to The World, with Burnand and Lewis each claiming to have hosted it. Andrew Lamb has concluded that the run-through at Burnand's home on 23 May 1866, without costumes or sets, was a rehearsal before a small group of invited friends, followed by the first performance at Lewis's home on 26 May 1866. A printed programme dated 23 May later surfaced, suggesting more than a mere rehearsal, but the composer himself supported the later date, writing to The World: "I feel bound to say that Burnand's version came upon me with the freshness of a novel. My own recollection of the business is perfectly distinct". John Foster, who played Bouncer in the production, called the run-through at Burnand's house a rehearsal. The original cast also included George du Maurier as Box and Harold Power as Cox, with Sullivan improvising the accompaniment at the piano. A review in The Times commented that Burnand had adapted Morton's libretto well, and that Sullivan's music was "full of sparking tune and real comic humour". The rest of the evening's entertainment included a musicale by the Moray Minstrels, the play A Wolf in Sheep's Clothing and Les deux aveugles. The opera was heard with a full orchestra for the first time on that occasion, with Sullivan completing the orchestration a matter of hours before the first rehearsal. The Musical World praised both author and composer, suggesting that the piece would gain success if presented professionally. It was repeated on 18 May 1867 at the Royal Gallery of Illustration in Regent Street. The critic for the magazine Fun, W. S. Gilbert, wrote of the 11 May performance:
right|thumb|Drawing of [[F. C. Burnand|Burnand in Vanity Fair]]
