Used as a prayerbook as well as a book of hymns for church services, the psalter in the later middle ages was often produced with a calendar and additional prayers. Eventually it was combined with an abridged version of the breviary, the prayerbook used by monks, to form the special lay prayerbook, the book of hours. This psalter represents an important stage in this development as it took place in England. It is one of the earliest psalters to include the Hours of the Virgin, a special set of devotions taken from the breviary. Also it is the earliest of a line of richly decorated psalters which were probably made at Oxford, in the workshops by lay scribes and artists, an industry which grew out of book production for the university. A collection of canticles and prayers follow the psalms in this book. A prayer to the Virgin and St John is presented with a title, in red, 'A Prayer to Holy Mary.' A plea for indulgence (forgiveness allowing release from time in Purgatory), the prayer appears in many later books of hours. The historiated initial shows a saint with a scroll, possibly intended to represent the author of the prayer or, more likely, St John the Evangelist with his gospel or Book of Revelations.