The only connection between Venice and Monteverdi's Vespro della Beata Virgine is that the 1610 collection of liturgical pieces was first published in the city. The composer was still based in Mantua, and there is no evidence that the Vespers was ever heard in Venice when he moved there three years later - no evidence either, that Monteverdi ever intended it to be performed as a single musical entity. But here the work was included as part of Fragments of Venice, the Southbank Centre's Nono festival, as if it told us something about the history of music in that city.

Had the concert been worthwhile, complaints about the programme planning would be irrelevant. Any excuse for performing Monteverdi's majestic score justifies itself. But this was a dim affair, in which the glories of that unapologetically showy sequence of choral and solos were submerged in the acoustic morass of Westminster Cathedral. From a seat halfway down the nave, the Westminster Cathedral Choir was uninvolving. The motets only sporadically acquired any dramatic presence, with the soloists - sopranos Julia Doyle and Cecilia Osmond, tenor Andrew Carwood - processing around the cathedral in a ridiculously self-conscious way to the accompaniment of unattributed organ solos. Baker's tempi - a few gabblingly fast, most ponderously slow - hardly helped, although when they got the chance, the instrumentalists of the New London Consort did show the fleetness and precision that should be the norm for Monteverdi performances. The rest was both dreary and precious, and Monteverdi's genius deserves far better.

· Fragments of Venice continues until October 31. Box office: 0871 663 2500.