The number of partbooks surviving is quite considerable, but complete sets are very few. These few include the important Forrest-Heyther and Gyffard sets and the source of Ludford's Lady Masses, British Museum Royal Appendix MSS. 45-48. The Peterhouse and Christ Church sets both lack their tenor books; reconstruction is easy where proper plainsongs in equal notes are involved, but at other times it is an awkward task.
The Gyffard partbooks (British Museum Additional MSS. 17802-5) are an invaluable source for smaller-scale works for the Sarum rite by Taverner, Tye, Tallis and Sheppard in particular: concordances have been traced for only three out of ninety-four pieces. The basic arrangement is: music for the Lady Mass, including Kyries and Alleluias; works for the Office in liturgical sequence from All Saints to Whit Sunday; the Proper of the Jesus Mass, and the three Masses Apon the square; Magnificats; and votive antiphons.
The books were copied in the middle years of the sixteenth century. Work on them may have begun 'as early as the 1540s', but much or most of it was probably done during the Marian reaction of 1553-8, by which time William Mundy and Robert Whyte (b. c. 1530) could have been composing. It would be easy to assume that the manuscripts were still incomplete when Mary died, for the name of 'mr birde' appears. But in fact the man who composed In exitu Israel jointly with Sheppard and William Mundy is probably not the great William Byrd, but Thomas Byrd, Gentleman of the Chapel Royal 1546-8, or the William Byrd who was a chorister at Westminster Abbey when William Mundy was head of the choristers there in 1543-4. Similarly it seems rather improbable that the John Mundy who composed a Kyrie was William Mundy's son John who died in 1630; possibly William had a brother John, or possibly the Christian name is wrong. The Gyffard partbooks show no sign of use, and contain many uncorrected scribal errors. But if designed for liturgical use under Mary, the brevity of their 'working life' might be sufficient reason for this.
The Christ Church Oxford partbooks (MSS. 979-83 ) were copied between about 1580 and 1600 by John Baldwin, who had a hand in completing the Forrest-Heyther manuscripts and who kept a fascinating musical commonplace-book sometimes known as the Baldwin manuscript. The Christ Church books are beautifully neat, and have been used little if at all; they probably formed a kind of private musical treasury. Today they are the leading source for compositions written in the last years of the Sarum rite (especially for numerous responds and hymns by Sheppard and Tallis), and an important one for Latin works composed under Elizabeth. It is interesting to note that some works by Fayrfax and Taverner are still included, as indeed they are in other late sixteenth century manuscripts.
Gyffard has works by four men known also from Peterhouse: Knyght (with three works, including a stylish Alleluia Obtine sacris), Appleby (whose Mass for a Mene is a rather pedestrian effort in something of the same style as Taverner's similarly titled piece), Bramston, and Whytbrook (composer of a Mass Apon the square briefly noted in the article on William Mundy). Other composers, most of them represented by single works, include Philip Alcoke, Robert Barber, (?Thomas) Byrd (joint composer with Sheppard and Mundy of In exitu Israel), Robert Cooper, John Ensdale, John Hake, Christopher Hoskins, Hyett, Robert Okeland, Stenings, and Thomas Wryght. Finally there are three composers known also from the Christ Church partbooks: Robert Johnson, John Redford and Philip van Wilder. Gyffard has unusually many anonymous pieces for a mid or late sixteenth-century source, eighteen out of ninety-four. There is a St Matthew Passionand four settings of the Asperges(these seem to be among the oldest works in the manuscript), aVidi aquam, a setting of the Jesus Mass Proper, aKyrie, aTe Deum on the faburden, several responds and short antiphons.
Christ Church contains Wood'sExsurge Domineand a Dum transissetby John Strabridge. There are a few Continental pieces includingIn convertendoand Ubi est Abel, ascribed to (Robert) Douglas, a Scot, but by Lassus.