This "leaf " is actually a montage of vellum cuttings excised from one or more service books taken from the Sistine Chapel during the 1798 French occupation of Rome. These cuttings were brought to England by Luigi Celotti (1759–1843), who presumably created the montage and sold it at Christie's on 26 May 1825, lot 87. In the Celotti sale catalogue, William Ottley (1771–1836) listed it under Pope Gregory XIII and attributed it to Giulio Clovio (1498–1578). It was then in Ottley's own sale at Sotheby's (10 May 1838, lot 243).