Conor Mitchell’s Abomination: A DUP Opera, a scathingly brilliant satire about homophobia, hate speech and the people who perpetrate it, comes to the Brighton festival after performances in Dublin and London with the same cast that gave the Belfast premiere in 2019. The opera’s starting point is Iris Robinson’s notorious Radio Ulster interview with Stephen Nolan in 2008, during which Robinson, a Democratic Unionist Party MP and wife of Northern Ireland’s then first minister, was asked to reflect on her previous description of homosexuality as “an abomination” in the wake of a recent attack on a gay man in Belfast. Robinson refused to retract her comments, and went on to recommend the services of “a lovely psychiatrist” who peddled conversion practices. The interview, set verbatim, forms the basis of Mitchell’s libretto, though he expands the text with quotes from other DUP members, whose comparable expressions of prejudice are sung by an ensemble of four vocalists and streamed as newsprint or documentary footage across screens behind the performers. Mitchell in part allows his politicians to skewer themselves with their own words, though the real brilliance here lies in the scorn to which his music subjects their appalling utterances. Rebecca Caine’s Iris praises her psychiatrist to a waltz that could have strayed from Massenet, and responds to Nolan (actor Tony Flynn) with Straussian melismas that glide evasively around the words. Bile is undercut by camp in They Are Poofs, a marvellous mock-Rossini ensemble for the vocal quartet. A chamber orchestra, meanwhile, adds bitter instrumental comments of its own in Stravinskyan or minimalist style. Caine gives a terrific central performance as Iris, sumptuously sung, acted with considerable subtlety, and beautifully foiled by Flynn’s Nolan: we really sense the principled anger beneath the man’s unflappable surface calm. The vocal quartet are marvellous, with actor and drag artist Matthew Cavan at once particularly outstanding and gloriously camp, while the Belfast Ensemble’s orchestra play wonderfully well for Tom Deering. Mitchell directs himself with clarity and sparse yet telling detail. Political satire in opera is relatively rare and often unsuccessful despite the achievements of Offenbach and Kurt Weill in Weimar republic mode. Abomination, however, more than holds its own in such exalted company. At the Theatre Royal, Brighton, until 10 May