The British Library manuscript Royal 12 D. xvii contains three books of medical material. Cockayne referred to the collections in this manuscript as a Leech Book, which he then further divided into three volumes. However, he recognised the third book as having a different ‘somewhat more monkish character’, and it is now widely agreed that these three volumes actually represent two separate collections of medical material. The first two books of the Royal manuscript are commonly referred to as Bald's Leechbook: the best known and likely oldest of the Old English medical collections, which, as such, represents the earliest complete medical collection in a Western vernacular. The final book is identified by scholars as Leechbook III (a name taken from Cockayne's original idea of a Leechbook in three parts) and will be the focus of Chapter 2.

The name Bald's Leechbook is taken from a verse colophon that occurs at the end of the second book. This colophon, which serves to divide the two books of Bald's Leechbook from Leechbook III, is written in Latin hexameters:

The colophon has attracted some attention because it associates the collection with an author (this is the only one of the four Old English medical texts to be associated, however tenuously, with a named author). The names themselves are unusual and it seems most likely that they are shortened versions of longer names. Both ‘Bald’ (or ‘Beald’) and ‘Cild’ appear much more often as a component in Anglo-Saxon names rather than as a name themselves. The shortened versions are probably given to meet the requirements of the hexameter verse.