IN the welter of new music and new interpretations that made London this week the epicentre of musical activity, Roxanna Panufnik's Westminster Mass, which received its first performance on Thursday, was a jewel.

Quite simply, set alongside Robert Lepage's extended Mahlerian ruminations in Kindertotenlieder and the monstrous pretensions of Robert Wilson and Philip Glass's Monsters of Grace, Panufnik's exquisite Mass setting - a relative model of clarity, and written from the heart - was the best music on offer in London.

The Westminster Mass was commissioned to celebrate the 75th birthday of Cardinal Basil Hume, who was the principal celebrant in the Ascension Day Mass during which Panufnik's new composition was performed by the glorious Westminster Cathedral Choir and the City of London Sinfonia.

Obviously, in the context of the solemn Mass for which it was written, with its seven sections separated by and scattered through a lengthy liturgy, the new music had little cumulative impact.

But, at its rehearsals and run through in the afternoon, conducted by the cathedral's master of music, James O'Donnell, it was clear that the piece is an absolute entity, and, as a musical composition, stands on its own, coherent and convincing.

And it is a beautiful composition, sensitively orchestrated for strings, harps, and tubular bells. Its ethos is romantic but never over-the-top, sweet but unsentimental, and characterised by rich, gentle harmonies and a devotional, quietly fervent sense of atmosphere. It also has a number of melodic hooks (principally in the Kyrie, Gloria, and an undulating motif in the Agnus Dei) that are instantly memorable.

This, like the best of its type, is a Mass that will travel and be taken up - for purely musical performance - by a range of choirs and chamber orchestras. It's ravishing.