Among the musical treasures in the British Library is a sumptuous choirbook prepared for Henry VIII and Catherine of Aragon. It was produced by Petrus Alamire, who not only headed one of the finest musical scriptoriums of the age but acted as a spy for Henry against Plantagenet claimant to the English throne Richard de la Pole. Gifted to the royal couple c. 1516 it contains 34 motets, many unique to this manuscript, and includes masterworks by leading French and Franco-Flemish composers of the age including Josquin Desprez, Jean Mouton, Heinrich Isaac, Antoine de Fevin, and Pierre de la Rue.