Rubens was in Madrid from September 1628 to April 1629 as an envoy of the Archduchess of Austria, Isabella Clara Eugenia (1566-1633). Michael Jaffé states in his article (M. Jaffé, ‘Rubens’s Portrait of Isabelle de Bourbon, Queen of Spain’, Artibus et Historia, vol. 13, no. 26, 1992, pp. 9-14.) that between his diplomatic duties he had been granted sittings with all members of the Spanish royal family, to paint their heads. Rubens painted his study of Isabella de Bourbon in the autumn of 1628. (sold at: Property of a Lady of Title; Sotheby’s, London, 26 July 1972, lot 8, removed from Stobo Castle, Peebleshire.) Jaffé suggests that the studies were brought to Rubens’ studio and were used to paint portraits for the Infanta Isabella. They would have been kept to be used as models for larger portraits that were required for official purposes. The present lot is presumably based on this study.