Mostly Mozart, Barbican, London

It may feel like autumn, but as the annual head-to-head begins between the Barbican and the BBC, it must be summer.

It may feel like autumn, but as the annual head-to-head begins between the Barbican and the BBC, it must be summer. True, the Barbican has a head start with its Mostly Mozart festival, which has just begun, a week's whisker ahead of the BBC Proms.

Mostly Mozart, now in its third year, is a neat festival. It runs on Thursday to Saturday every week in July; has a clear artistic profile - 18th-century repertoire, with Mozart taking the lion's share, plus a sprinkling of 19th-century works (Beethoven's Fifth and Ninth Symphonies and a Weber horn concerto) - features up-and-coming young artists; includes a Mixing Mozart Family Festival, where children aged eight and above sing and play Mozart, even creating a composition based on Mozart shepherded by the Academy of St Martin in the Fields; and is seen by the Barbican as providing an entry to newcomers to classical music - 60 per cent of the audience last year was new to the Barbican.

Mostly Mozart is a clever copy of New York's Lincoln Center festival, and this year its director, Louis Langrée, opened the first weekend in London. With the exception of one concert, the Academy of St Martin in the Fields is the "house" orchestra. Mozart's 40th Symphony and the Requiem hardly feel like celebratory music to begin a festival. But there's nothing wrong with throwing a serious programme at an audience that may not all be familiar with Mozart at his greatest. This capacity crowd not only looked younger but did not feel like regulars; the queue for returns was one of the longest I've ever seen.

Langrée, who has just enjoyed considerable success at Glyndebourne with Debussy's Pelléas et Mélisande, brought a restless rigour to his Mozart. Seldom can I remember Mozart at such speed, the minuet of the 40th coming over as positively militaristic rather than dance-like. At such a tempo, the fourth movement made less contrast with the previous movement, the extraordinary tonal vagaries almost lost to the hectic, almost Beethovenian pace. Nevertheless, the furious antics of the chamber-proportioned orchestra, trying to articulate all the notes and keep up, was certainly striking.

Langrée again adopted fast tempi for the Requiem which only became somewhat calmed with the entry of the bass soloist, Andrew Foster Williams, in the "Tuba mirum" who clearly wanted a slightly slower tempo. John Mark Ainsley followed in similar vein, most beautifully phrasing mors stupebit... and encouraging a more expansive feel. Langrée then whipped up the speed again in the "Rex tremendae" and the "Confutatis" allowing for maximum contrast with the intervening "Recordare". Langrée, using Franz Beyer's "cleaned-up" version of Süssmayr's completion, brought heartbreaking weight to the "Agnus Dei". The choristers of the 26-strong Polyphony, although initially overwhelmed by the orchestra, really came into their own in the Offertory, the male altos adding a particularly piquant colour. The soprano Lisa Milne and the mezzo Karen Cargill completed a finely balanced quartet of soloists. The basset-horns and trombones provided thrilling colouring, the hard-sticked timpani rigorous rhythm. Unmissable Mozart.