'Iolanthe' is one of his most enrapturing confections, the story of a shepherd, Strephon, half-fairy half-mortal, whose mother, Iolanthe, is a disgraced sprite (it is forbidden for fairies to marry mortals), and whose father (unbeknownst to either) is the Lord Chancellor who won't let him marry his ward, Phyllis, darling of the Lords.
The material may be fantastic, the setting pastoral, but the satire in this 1882 work is spot-on contemporary, with jibes at the Irish problem, the uselessness of the House of Lords (who as a caste are as close to fantasy as the fairies, so it is no surprise they exchange the House of Peers for the House of Peris), and the ruling class' fear of democracy and universal suffrage. A most delightful fancy has the fairies take over Parliament in the shape of Strephon, whose every whim unites the notoriously factional Liberal and Conservative in his favour.
this is Gilbert at his funniest - the verbal contortions he undergoes in the search for rhymes break all linguistic boundaries, and his view of the fragility of centuries-old English institutions prescient. There is an extraordinary patter song by the Lord Chancellor which shows the man embodying Law and Constitution plunging into nightmare, the culmination of a libretto in which identities and forms, as well as seemingly irrevocable laws and customs, are repeatedly broken down or metamorphosed.