Gilbert and Sullivan's comic opera H.M.S. Pinafore opens at the Opera Comique in London.

Gilbert and Sullivan refers to the Victorian-era theatrical partnership of the dramatist W. S. Gilbert (1836–1911) and the composer Arthur Sullivan (1842–1900) and to the works they jointly created. The two men collaborated on fourteen comic operas between 1871 and 1896, of which H.M.S. Pinafore, The Pirates of Penzance and The Mikado are among the best known.

Comic opera, sometimes known as light opera, is a sung dramatic work of a light or comic nature, usually with a happy ending and often including spoken dialogue.

H.M.S. Pinafore; or, The Lass That Loved a Sailor is a comic opera in two acts, with music by Arthur Sullivan and a libretto by W. S. Gilbert. It opened at the Opera Comique in London on 25 May 1878, and ran for 571 performances, which was the second-longest run of any musical theatre piece up to that time. H.M.S. Pinafore was Gilbert and Sullivan's fourth operatic collaboration and their first international sensation.

The Opera Comique was a 19th-century theatre constructed in Westminster, London, located between Wych Street, Holywell Street and the Strand. It opened in 1870 and was demolished in 1902, to make way for the construction of the Aldwych and Kingsway.