Susan Hellauer's lucid introduction to the contents of Jacobus, the Liber Sancti Iacobi (the Codex Calixtinus) makes fascinating reading. Following Christopher Hohler, she points out that this extraordinary collection of liturgical items, non-liturgical pilgrim songs, sermons, chants and lessons in honour of St James, was originally destined for the use of French schoolboys, presumably with voix blanches. That being so, this recording by a group of high female voices may be easily vindicated: Anonymous 4 bring to their performance that smooth, unsophisticated vocal blend we have come to expect from them. It is a lovely sound, and their intelligent and imaginative approach sticks resolutely to middle ground, avoiding excesses of orientation and extremes of interpretative theory.