Saint Zeno exorcising the Daughter of the Emperor Gallienus: Predella Panel

A small black demon slips out of a girl's mouth as Saint Zeno, bishop of Verona in the 4th century, drives it out of her. Her parents watch anxiously, and the father, kneeling in a crown, is the Roman emperor Gallienus. In the legend the grateful emperor then let Christians practise their faith freely across the empire. The dates do not quite fit, since Gallienus died in 268, almost a century before Zeno became bishop.

This was one of five scenes along the foot of the altarpiece. The fifth, a vision of Saint Augustine on the seashore, was recognised in 1996 in the Hermitage in St Petersburg, and that year it was lent to London and shown beside the others for about three months.