The Battle of Bosworth in 1485 marked the start of the Tudor dynasty. It had an added significance for Wales as it marked the start of a period of greater political stability, further strengthened by the Act of Union between England and Wales, 1536/43. Stability was far from reality for the Church, however, with fundamental changes in church governance emanating from Henry VIII's break with Rome in 1534. This thesis investigates the changing demands placed upon the church musician and provision for music in the liturgy in a variety of Welsh and borderland ecclesiastical institutions. The geographical area is extended beyond Wales to include (as a means of a comparison) those towns of the counties of Cheshire, Shropshire and Herefordshire which lie either on or west of the main north-south thoroughfare, namely Chester, Oswestry, Shrewsbury, Ludlow, Leominster and Hereford. The scope of the thesis is naturally broad ranging. It advances our knowledge of church music in the region by drawing together and reconciling the fragmentary research of other historians and musicologists in addition to much original research. Important historical features of medieval Wales and its Church are presented to provide a background for the subsequent analysis of the liturgical and musical specifics of the immediate pre-Reformation period. The remaining chapters look in detail at the postReformation situation. Comparisons are drawn and any regional characteristics noted, especially with regard to the choral repertoire and the use of the organ. The final date, 1645, is a convenient point at which to end this study since officially this was when public worship from the Book of Common Prayer was outlawed, choral services eventually brought to a standstill until the Restoration of the Monarchy in 1660