This Missal, or service book for the Mass, is one of the rarest items presented to George III by the book collector Jacob Bryant. It is one of seven extant copies (of which four are incomplete) and the only one printed entirely on vellum. It was produced in Rouen, the third most prolific printing centre in France after Paris and Lyon, for the English market. It follows the Use of Sarum, the form of the Mass used in Salisbury and its neighbouring dioceses, which was the most widely accepted Use within England until the Reformation. Its most striking deviation from the Roman rite were its elaborate ceremonials, particularly in the rituals leading up to and during Easter, when several imposing and colourful processions were staged.

Bibliographic description
[8], CCLXXIX vellum leaves measuring approximately 357x250 mm. Printed signatures: a⁸s A-E⁸ F⁶ G⁸ H⁶ I-L⁸ M⁶ N-S⁸ T-X⁶ a-c⁸ d⁶ e⁸ f⁶ g-p⁸ q⁸ (q8 cancelled). Includes printed music (black notes on red staves). Text arranged in double columns of 40 lines, ruled by hand at the outer margins in red ink, printed in black and red; running headers; foliation in Roman numerals at the top right corners. Decoration includes half-page woodcuts (St George slaying the dragon at f.[1]r, the first Sunday of Advent at f.Ir, the crucifixion at f.CIv, St Peter and the four evangelists at f.CIIr, the resurrection at f.CVIIr, St Andrew's martyrdom at f.CLVIIr, and a set of four religious vignettes at f.CCXVIIr), one inhabited initial in red at f.XIVr, and simple initials in red throughout. The woodcuts have been hand-painted using gold, blue, red, and green. Ms. white decorated initials on gold background and floral motifs. Simple ms. initials in blue with red penflourishes; printed guide-letters are sometimes visible underneath. The names of saints, martyrs and popes, as well as longer sections of the Mass, have been erased with a knife throughout.

Binding description
Armorial binding in brown calf skin rebacked by Richard Day. Covers with onlaid black calf central panels, decorated with gilt fillets to form a border and panel with floral tools at the outer corners; arms of George III as centrepiece. Spine with six raised bands, decorated with blind tools and gilt titling. Tetxblock gilted. Endpapers of plain paper.