This study traces the career of a single illuminator (the Ancient 6 Master) who was active in England from c. 1310 to 1335. For much of this time it can be shown that he worked in collaboration with the artist of Queen Mary's Psalter, one of the most profusely illustrated English manuscripts in existence Although a large number of books have been grouped under the heading of the ‘Queen Mary’ style, they have never received a proper classification, nor has any detailed attention been given to the problem dating. This paper attempts both to isolate the works in which the two artists participated and to propose a sequence ofproduction. Since most of these manuscripts are devoid of internal documentary evidence for dating, a chronology has been devised on the basis of the Ancient 6 Master's artistic development; this has involved an investigation of minor aspects of style. As a result, it has been possible to learn about the career of the Queen Mary Artist, and by virtue of the few firmly datable manuscripts, viewed in the light of the chronology proposed, dates have been suggested for the others within this group.