A chiaroscuro drawing of St Gregory kneeling in the foreground, with a procession of many clerics beyond, leading over Ponte Sant'Angelo to the Castel Sant'Angelo in the distance. St Gregory and several others look up to the right, towards an apparition not visible in this drawing. Cut to an arch, apparently cuting away what must have been the apparition of St Michael on a lost portion to the right. Inscribed below with a collector's number '56'.

Popham (in P&W): 'The drawing may have some connection with the altarpiece of the subject in the Madonna del Baraccano, Bologna (Venturi, IX 6, fig. 465), though the correspondence is general and no single figure is the same. According to Malvasia (ed. 1841, p. 250) the picture in question was supposed to have been painted by Cesare Aretusi from a drawing furnished him by Prospero Fontana in place of one, ordered of Federico Zuccaro, which did not give him satisfaction. 
'This theory is accepted by Venturi but not by Corrado Ricci (Rassegna d'Arte VII, 1907, p. 102) or by Werner Körte (Der Palazzo Zuccari in Rom, Leipzig 1935, p. 75). It is in fact known that Ferderico Zuccaro was commissioned by Paolo Ghiselli in 1580 to paint this subject for the church in Bologna, and both Ricci and Körte believe that the picture in the church is Zuccaro's. Ricci further published a drawing from the Santarelli collection in the Uffizi for the picture, which seems to be by Federico. The present drawing is certainly not his and almost certainly Bolognese. It is likely to be the modello by another artist, but hardly by Prospero Fontana, to judge from the style. This seems nearer to Ercole Procaccini's, but in the absence of any authenticated drawings by that artist it is better to leave it anonymous.'

Popham later [where?] noted a correspondence with a drawing by FZ in Munich, repr. in Der Maler Federico Zuccari, p. 140. A note in the BM desk copy of P&W reads 'See Venturi IX(5) 642 & 891, IX(6) 760'.

The drawing was included in Blunt (Misc.), no. 570, as 'Eighteenth-century Bolognese', but this is clearly incorrect and there must have been some error in the compilation of that catalogue.