Alfred Jarry's play Ubu Roi is one of the most celebrated parodies of dictatorship and political opportunism. But in Polish composer Krzysztof Penderecki's operatic adaptation, Ubu Rex, Jarry's savage satire is reduced to a bland soap opera of power and propaganda. The piece was the climax of the Polish National Opera's short season at Sadler's Wells, in a lavish but ill-conceived production. Directed by Krzysztof Warlikowski, it was long on ambition but short on achievement.

Composed in 1991, the action of the opera is set in contemporary Poland, and sees the oafish Ubu stage a murderous coup d'état, killing King Wenceslas and instituting a reign of terror before he is defeated in a war with the Russians. Penderecki's own libretto turns this drama into a skit on the end of communism in Poland: "We're all waiting for the free market economy," Ubu laments in his first public proclamation as king. But that is as profound as the satire gets. The main culprit is Penderecki's music. A clunking neo-classical parody, the score references everyone from Mozart to Mussorgsky, but remains a lifeless grey. An acerbic fanfare symbolises the emptiness of Ubu's dreams of power, but after its obsessive repetition, the melody ends up sounding vacuous. The score is full of musical and dramatic jokes that don't work and Penderecki contrives to botch the dramatic gifts presented by the story: the murder scene, which could have been full of black humour, is instead a heavy-handed anti-climax; the scene in which Ubu systematically murders his entire government is clumsy and routine, without any sense of shock.

In the midst of an over-the-top production (which staged the war between the Poles and the Russians as an unarmed combat between two teams of gymnasts) tenor Pawel Wunder's performance in the title role was a heroic achievement; but even his energy and virtuosity could not save the piece.