Even by the standards we normally expect of Ockeghem, the Missa Prolationum is at first glance craggy and uninviting; but on further hearing it can be uniquely attractive, certainly so in this performance by Lucien Kandel and Ensemble Musica Nova. As in the gentler recording of The Clerks’ Group under Edward Wickham (1995), they have two singers to a part, with women on the top line – though here with second voice shared between a male (Kandel himself) and a female singer. For an all-male performance we must go to Paul Hillier and the Hilliard Ensemble (1989), with just four solo voices (and with two of the same accompanying motets). Current historical opinion favours grown men alone for this music and feels that mixing men and women in church is hard to document; but we are now used to hearing this music with mixed ensembles and must be happy that they do it so well.

What is so attractive about Ensemble Musica Nova is the way they sing out and are not afraid of the close miking (which makes the breathing occasionally sound more self-conscious than it perhaps should). But most of all they entirely hide the mind-boggling difficulty of composing many passages in the piece, with its mensural canons at all possible intervals. Gérard Geay’s accompanying note explains some of the issues involved.

Still, it may be better just to admire the beautiful ensemble of the group, their excellent tuning and their effortless control of the vocal lines, which are among the most initially unyielding of any music from the 15th century. The two motets that begin and end the disc bring us back to more familiar ground.