The attribution to Federico Zuccaro has kindly confirmed by James Mundy on the basis of a photograph in a communication dated 24 October 2003. Mr. Mundy indicates that the drawing is a study for a compartment in a ceiling decoration possibly for the Palazzo Bonelli in Rome, known through a drawing in the Staatliche Graphische Sammlung, Munich (inv. 3402, J. Mundy, Renaissance into Baroque, Italian Master Drawings by the Zuccari, exhib. cat., Milwaukee Art Museum and elsewhere, 1989, pp. 161-3, fig. 19).
The drawing in Munich bears the arms of Pius V, elected pope in 1566, and those of his nephew, Cardinal Bonelli who received the Cardinal's hat from his uncle the same year, dating the commission to 1566 or soon after.