Purcell’s only five-part fantazia (Z745) gains its title ‘upon one note’ from the middle C which sounds throughout. From the first bar Oliver Knussen begins to distort the rhythms and pitches of his model while retaining the fixed C, which thus finds itself surrounded occasionally by very alien harmony indeed. As though out of a mist, the diatonic tonality of the original emerges from time to time to mark the ends of the sections, which follow the same plan as those of Fantazia 7 (Benjamin). During the final fast section Purcell’s music re-asserts itself unequivocally so that the closing bars are entirely as he wrote them.

© Mark Edgley Smith