The attribution to Reni was confirmed by Dr Catherine Johnston in a letter dated 5 March 2007. Dr Johnston relates the head to that of Saint Petronius in a votive standard on silk, the Pala della Peste showing The Madonna and Child in glory appearing to the patron saints of Bologna, painted in 1631 at the order of the Bolognese Senate following delivery from the plague the previous year (D.S. Pepper, Guido Reni, Oxford, 1984, no. 135). The drawing differs from the painting in minor details of drapery and hairline, indicating that it is one of Reni's characteristic large head studies made in preparation for the painting rather than a drawing made after the finished work. Only two other drawings for attendant saints in the Pala della Peste are known, a head study for Saint Proculus, now at Christ Church, Oxford (J. Byam Shaw, Drawings by Old Masters at Christ Church, Oxford, Oxford, 1976, no. 966) and a half-length study for Saint Ignatius Loyola, now in the Biblioteca Nacional, Madrid (V. Birke, Guido Reni, Zeichnungen, exhib. cat., Vienna, Albertina, 1981, no. 120). The drawing at Christ Church was formerly in the collection of Padre Resta, and bears the characteristic inventory number 'e.80'. The following drawing, 'e.81', is listed in the Richardsons' transcription of Resta's catalogue (British Museum Landsdowne MS 802) as a 'S. Petronio'. Sadly no inventory number can be discerned on the present drawing to confirm whether it shares the same provenance.