Byzantium Festival, Queen Elizabeth Hall, London

The Byzantine Festival in London 2004 bears the portentous subtitle The Women, Wealth and Wisdom of Byzantium. Concerts, words and music, talks and a feast, take place throughout March in various London venues including St Paul's, the Great Hall of the Hellenic Centre and the South Bank. Quantities of artists have come from all over to perform.

But on the strength of Tuesday's concert, ambition vastly outstrips delivery. The festival ostensibly focuses on one Byzantine woman, Kassiani, a ninth-century poet, composer and abbess who achieved fame by demonstrating a feisty disdain for a noble suitor (Emperor Theophilus) after he said - while selecting a bride from a bride-show - that women were the source of sin (ie, Eve). Kassiani's retort was that they were the source of salvation (ie, Mary, the mother of Christ). She took up monastic life, and he lived to regret it.

Despite the declared Kassiani emphasis, Tuesday's concert was called "Patricia Rozario Sings Hildegard", a nod toward that other colourful abbess Hildegard of Bingen, and it was with pure-ish Hildegard that the a cappella concert began. Rozario, resplendent in pale-blue sari, intoned Bingen's formulaic phrases over a continuous unison vocal drone from eight men in black. Too bad the men couldn't agree on pitch. And Rozario's voice is showing its age; where once she floated so high and so purely, the edges are now distinctly frayed.

A world premiere by Ivan Moody - protopsaltis and choir director of the Greek Orthodox Church in Lisbon - took us not to Kassiani but to St Catherine. The Passion of St Catherine for seven singers (six women and a male alto) was performed by the US West Coast group Cappella Romana, conducted by Alexander Lingas. "Chromatic" octaves (unisons easing in and out of pitch), pedals and drones in a homophonic texture with many a passing glance at Arvo Pärt could not disguise distinctly pedestrian writing.

With Christos Hatzis's De Angelis, we were back with Hildegard (and Rozario), an entire setting of her O gloriosissimi embedded in this work for chamber choir, three contraltos and soprano. A less suitable acoustic than the QEH for a vocal, antiphonal work would be hard to imagine. Slow, lugubrious chant, occasionally giving way to Michael Haydn-ish derivation, must have had H-of-B turning in her grave. Michael Adamis' Radiant Cloud for expanded Cappella Romana brought more slow, meandering chant as did John Vergin's When Augustus Reigned - academic religious music, although the text was by Kassiani. Let Not the Prince be Silent by Sir John Tavener rounded off a dismal evening, with Guy Protheroe conducting the combined English Chamber Choir and Cappella Romana complete with widely wobbling vibrato and questionable pitch.