The Smithfield Decretals (British Library, Royal MS. 10 E.iv) is an exceptionally large (c.450 x 285mm.) and lavish (including more than 600 narrative bas-de-page scenes) copy of the Decretals of Gregory IX with the gloss of Bernard of Parma, thought to have been written in southern France c.1300, with decoration and an extra prefatory quire added in England some decades later.
The BL website has an online description
with partial digitization and a description with full digitization
The main reason I found fault with a recent monograph on the Taymouth Hours is that it tends to treat hypotheses as facts. One of several such hypotheses is the proposal that the Smithfield Decretals was made for man called John Batayle who was a canon of St Bartolomew's, Smithfield, in the last quarter of the 14th century. This may be true, or it may not.