Between 1295 and 1313, the Archbishop of Canterbury, Robert Winchelsey, issued his constitution which required certain service-books to be provided by the parishioners for all parish churches within the province of Canterbury ‘… quod parochiani teneantur invenire infrascripta, videlicet, legendam, antiphonarium, gradale, psalterium, missale, troparium, ordinale, manuale …'; and that they should also be responsible for the repair or replacement of these service-books, which were the lesson-book, antiphoner, gradual, psalter, missal, troper, ordinal and manual. Winchelsey's constitution did not stop at books. Vestments, Mass plate, altar plate, bells, images, fonts, glazing and anything pertaining to the nave and beyond, even to the churchyard walls, became the responsibility of thechurchwardens and, through them, the parishioners. The chancel remained in the care of the rector.

It is impossible to say how the parishioners within the deanery of Dunwich reacted to Winchelsey's constitution, but, from the surviving inventories of 1368 made by order of the archdeacon of Norwich, it appears that within the 358 churches in his archdeaconry, most of the obligatory accoutrements, including the service-books, were present. There is no reason to think that the archdeaconry of Suffolk would have shown visitation returns deviating greatly from those of the archdeaconry of Norwich, and although later evidence from the Deanery wills may be sparse, it is possible to show that the responsibilities of the parish were undertaken by many testators.

The eight essential books specified by Archbishop Winchelsey encompassed both liturgical and musical requirements for church services, and any book considered necessary, over and above these, should be provided by the incumbent. Clerical wills show that there was appreciable responsibility on the part of the priests to ensure that their benefice, and frequently those of neighbouring rectors and vicars, possessed not only the books that were required under Winchelsey's constitution, but also texts which were additional to it. Nearly a quarter of all clerical wills in the Deanery contained book bequests.