The Yeomen of the Guard (2004)
It is set in the Tower of London during the 16th century, and is the darkest, and perhaps most emotionally engaging, of the Savoy Operas, ending with a broken-hearted main character and two very reluctant engagements, rather than the usual numerous marriages. The libretto does contain considerable humour, including a lot of punny-laden one-liners, and Gilbert's trademark satire and topsy-turvydom. The dialogue, though in prose, is quasi-Shakespearian in its language, being in early modern English. Despite its title, the opera is clearly about the Yeomen Warders rather than the Yeomen of the Guard. The character Sir Richard Cholmondeley, the Lieutenant of the Tower, is an actual historical figure.
Many consider the score to be Sullivan's finest. This was the first Savoy Opera to use Sullivan's larger orchestra, including a second bassoon and third trombone. Prior to Yeomen, Sullivan's standard pit orchestra had just one bassoon and two trombones. Most of Sullivan's subsequent operas, including those not composed with Gilbert as libretist, use this larger orchestra.