As part of his campaign to develop a library that met his essentially continental standards of what was appropriate for a bishop, Leofric, who held the see of Devon from 1046 to 1072, first at Crediton and then, from 1050, at Exeter, made a number of very careful additions to an assemblage of regulatory materials in English that had their origins in early-eleventh-century Worcester. These additions, also in English, reveal his appreciation of the purpose of the original manuscript materials, which were texts useful in exercising episcopal responsibilities. If, as is highly likely, this original core of vernacular texts was brought together under Wulfstan, bishop of Worcester 1002–16 and archbishop of York 1002–23, as Wormald has cogently argued, Leofric's subsequent interventions have the added value for modern scholars of demonstrating that he shared something of Wulfstan's interest in raising the standards of the secular Church. The manuscript in question survives now as Part B of Cambridge, Corpus Christi College, MS 190 (pp. 295–420). In its present form it is physically linked with a similar collection of regulatory materials in Latin: Part A of the same manuscript. Ker believed that the Latin and English materials were unified in one codex in the eleventh century, which would make Leofric the likely instigator, once he had made his additions, although this cannot finally be proved. What is beyond doubt, however, is that Leofric recognised that these two assemblages were effectively companion collections, and he treated them accordingly.