Gabrieli Consort and Players/Mccreesh, Barbican, London

What on earth, one wonders, were early performances of Beethoven's unprecedentedly vast and demanding Missa Solemnis actually like? Did the sopranos and tenors sag under the strain of sustaining their top notes fortissimo for bars on end? Were the strings and woodwind all over the place in the madly syncopated fugato in the "Dona nobis pacem"? Did the leader really attempt to scale that stratospheric violin solo in the "Benedictus" with such unmollified edginess?

If so, then the latest "period" performance by the 38 singers and 52 instrumentalists of the Gabrieli Consort and Players, under Paul McCreesh, was at times even more authentic than intended. Although the tendency of reedy bassoons and rasping horns to stick out intermittently from the textures could be attributed to Beethoven's oddly mosaic methods of scoring, and the fierce, dry harshness of the ensemble going full-blast could be blamed on the unflattering Barbican acoustic, there was also the matter of McCreesh's distinctly idiosyncratic direction.

This is a conductor who tends to wave his arms in bemusing curves and spirals, while giving the beat with his knees. While this may be conducive to expressive singing, it is less helpful to precision of ensemble or rhythmic attack. Both the "Kyrie" and the "Agnus Dei" were glutinously slow – the first disclosing some sour wind intonation, the second failing to accumulate its tragic, march-like tread. At the quicker tempo changes of the "Gloria" and "Credo", it occasionally took a bar or so for everyone to get back together.

And yet, and yet... out of the uncertainties of balance and rhythm, out of the very sense of living dangerously, maybe qualities were recaptured that have been lost to more smoothly accomplished modern readings. Where the soprano soloist Susan Gritton seized one of those brief, soaring, heart-stopping phrases that Beethoven occasionally interjects; where the choir and orchestra really got the bit between its teeth in the headlong rampages and joyous whoops of the "Gloria", one sensed how strange and wild the intensity of Beethoven's fervour must have sounded to its first audience.

After the "Gloria", a young conductor friend exclaimed to me in sotto voce bemusement: "It's absolutely crazy – but it's wonderful!" And so it was.