Performed by the Ambrosian Opera Chorus, with the London Symphony Orchestra.

Captain Corcoran and his gallant crew await inspection by Sir Joseph Porter who is going to marry Corcoran's daughter Josephine. Porter arrives, along with an "admiring crowd of sisters, cousins and aunts". But we find out from the Captain in a confidence disclosed to Buttercup, that Josephine is in love with Ralph Rackstraw, one of the crew. After Sir Porter makes a speech about the equality of Englishmen, Rackstraw confesses his love to Josephine. They are apprehended trying to elope. Dick Deadeye, one of Ralph's ugly peers, had fingered them.

Sweet little Buttercup, the bumboat woman, reveals that Rakestraw and the Captain, had been exchanged at birth. The Captain, now a "commoner" is able to admit his love for Buttercup, and all ends happily.

Among the three most popular of the thirteen compositions by G&S performed for the Savoy Opera House, this opera's humour focuses on love between members of different social classes. It is a lampoon of the British class system in general, and pokes good-natured fun at patriotism, party politics, the Royal Navy, and the rise of unqualified people to positions of authority. An intimate underwear garment for a woman, a "pinafore", is the given name of the fearsome warship.