This drawing was made by Masucci after he had completed his large painting showing the same subject, now in the Scottish National Portrait Gallery (PG 2415). Both works show the blessing of the marriage between Prince James Francis Edward Stuart (the Old Pretender), and Princess Maria Clementina Sobieska. Masucci has made some minor alterations to his original design, most obviously the subject of the frescoes on the ceiling of the room where the ceremony is taking place. His original painting included scenes from the life of the Emperor Constantine, but in this drawing he has shown two scenes from the Old Testament: `The Sacrifice of Isaac? and `Cain Killing Abel?. It is likely that Masucci made the drawing so that he had a personal record of the painting.