The German organist Johann Kaspar Kerll wrote three Cuckoo Capriccios, of which this is the first. It's a virtuoso piece, with the rapid passagework and tempo changes characteristic of seventeenth-century fantasias, all underpinned - and overlaid - by the ostinato cukoo. I hope I've done it justice. It requires good ensemble co-ordination, especially in the antiphonic 'cuckoos' with their varying volumes. Tempo and dynamics are editorial. Purists may quarrel with my choice of a slow tempo for the triple-time passages. But I sense these, for flutes at least, as gentle and pastorally evocative episodes. It's a brilliant tour-de-force for any concert.