"Mad Ireland hurt you into poetry," wrote WH Auden of WB Yeats. Mad Ireland has also clearly done something to Damien Dempsey, though the results barely qualify as poetry. A folk singer if he is anything, Dempsey sees himself as the voice of the disaffected Irish working class, telling it like it is: drugs are bad, fat-cat developers are bad, the government is bad, drinking too much is bad. Dempsey clearly means well, but even by the standards of folk music at its most austere, these songs - with the artist bashing away at his acoustic guitar - frequently sound less than musical.

Much of Dempsey's rhetoric makes the Tracy Chapman song that asked "Why do the babies starve when there's enough food to feed the world?" look like Chomsky. You can see, partly, why these songs would appeal to Sinead O'Connor, who provides backing vocals on Dempsey's album: there's the same inability to distinguish between passionate polemic and clumsy hectoring that gives many of her later records an unlyrical bent.

Morrissey, one of Dempsey's many vocal fans, commented that he had "the most beautiful voice in the universe". Given that Dempsey is a staggeringly well-put-together young man who could be Roy Keane's younger brother, you wonder whether perhaps Moz had something else in mind. A couple of songs have lovely, lilting melodies that Dempsey sings almost sweetly, and with comparative restraint. Mainly, though, his voice is a bludgeoning, gruff, adenoidal thing - a bad Irish Billy Bragg with a thick cold, or a cousin of the Proclaimers twins similarly afflicted.

Yeats, quite possibly, is turning in his grave. Dempsey, seemingly virtually incapable of treading softly, is thundering across Ireland in big, muddy boots.

· Repeated tonight. Box office: 020-7534 6970. Then touring.