The Smithfield Decretals is a copy of the glossed Decretals of Pope Gregory IX (r. 1227–1241), renowned for its extraordinary programme of marginal illumination. There are approximately 675 surviving manuscripts of this text, which was an essential work for legal study during the Middle Ages. Of this group, the Smithfield Decretals is by far the most extensively illuminated copy, with every one of its 626 pages of text embellished with imagery.

The volume was copied in the south of France, probably in or near Toulouse, at the turn of the 14th century. There it was decorated with illustrations that mark the beginning of each of the text’s five books. By 1340, the manuscript was in London, where its owner commissioned a group of local artists to add an illuminated list of the topics covered in the Decretals to the beginning of the text and to fill its wide margins with narrative images and decorative motifs.

The London illuminators painted two sets of borders on each page, one around the main text and another around the gloss (or commentary) and placed monsters, grotesques, and other scenes in the gaps between the columns of text. They also filled the lower margins with scenes, most of which recount stories that unfold over many pages. These narrative sequences relate tales from a variety of sources, including the Bible, saints’ lives and miracles, romances, moral fables, and parodies.

A series of images, which marks the beginning of the text, shows the promulgation, distribution, and study of the Decretals. A central illustration (image no 1), painted by a French artist, shows Gregory IX, accompanied by cardinals and clerics, organising the distribution of copies of the work.

By the 15th century, the manuscript was in the possession of the Augustine priory of St Bartholomew at Smithfield, located just outside London’s medieval walls. The ownership mark of the priory was inscribed on the manuscript’s first leaf during this time. It subsequently became part of the Old Royal library in the early 16th century.