The miniature of the Mass of St Gregory shows extensive flaking and loss of paint, especially along the top and right-hand side. These correspond to areas where the paper backing, onto which the leaf had been pasted, has been partially removed. These damaged areas were retouched in the late 19th century using cobalt blue and lithopone. The latter pigment was first produced c. 1850 and became widely available in 1874, allowing us to establish a post quem date for this intervention. Brass powder was used to retouch losses in areas originally painted with shell gold.
The partial paper removal as well as the restoration were probably carried out under the ownership of Charles Brinsley Marlay, who preserved the notes handwritten in 1856 by the previous owner Thomas Miller Whitehead, and then bequeathed the leaf to the Fitzwilliam Museum in 1912.
