Abstract: In articles published since the 1970s, I have gradually pieced together what remains of a royal choirbook of the 1420s. New fragments have turned up periodically, including some so far unpublished. Where the fragments could be related to book bindings which inadvertently ensured their survival, the binder was the early-16th-century Cambridge stationer Nicholas Spierinck. There are now 18 leaves or partial leaves, with parts of 32 or 33 compositions. The main criteria for linking them were the presence of one of two principal scribes, and the unusual high-quality monochrome initials, some with human or animal figuration, including lions and an antelope favoured by the Lancastrians, which point to royal patronage, possibly by the younger brothers of Henry V: John Duke of Bedford or Humphrey Duke of Gloucester or their stepmother Queen Joan. Some pieces were copied into the main body of the manuscript directly from additions to the Old Hall manuscript, probably while that book was still in use in the chapel of the infant Henry VI, because the new copies were made before corrections were made to the Old Hall versions. Considerable overlaps with Old Hall, and a very similar overall arrangement, also point to a royal provenance. I will assess the repertory, which gives some prominence to Dunstaple, who is present in Old Hall only as an anonymous later addition. I will show how the fragments are linked, including some later additions, and suggest a possible route for the manuscript’s final destination in Cambridge. I will also revise my proposed dating of Old Hall, to which the fragmentary choirbook gives some context.