John Taverner's Western Wind Mass, one of the splendours of Tudor church music, was the latest masterpiece to be presented in what, this year, looks increasingly like the Festival's musical mainstream. Forget Mahler at the Usher Hall. Greyfriars Kirk is where it is happening, and Paul Hillier's Theatre of Voices, singing to a packed church, yesterday ensured that we were aware of the fact.

Taverner composed both in Latin and English - prudently, it was said, because changes in monarch could bring reversions to the Roman rite. Infiltrated with old English interludes, Hillier's glowing, energetic performance, sung not only by his own ensemble, but by Ars Nova Copenhagen and sometimes by himself, was radiantly sustained and keenly controlled in acoustics for which it seemed impressively geared. Whether employing the full force of a dozen singers, or pared down to two or three voices, the music never lost its grip.

Yet it was not just Taverner to whom we were indebted for the experience. Thomas Tallis and Christopher Tye were represented in this inflation of Taverner's Mass, Tallis by his Salvator Mundi motet, Tye by the exquisite respond, In Pace (In Peace), which sent people out at 7pm to other events or simply to walk and think about what they had heard.

Next week come the Flemish Huelgas Ensemble with Orlande de Lassus, England's Tallis Scholars with Palestrina, Italy's La Venexiana with Gesualdo and Germany's intimate Cantus Colln with Bach motets. Maybe Mr Mills should think of giving us an annual early music festival-within-a-festival.