This is a study in the social and political history of England and Wales in one of its most turbulent periods - that of the 15th and early 16th centuries, when the ancestors of the present Lord Dynevor was one of the two or three most significant families in Wales. They played a central role in the Wars of the Roses in Wales. Their most famous member, Rhys ap Thomas was the focus of support for Henry Tudor in 1485 and at the Battle of Bosworth, and he and his son, Gruffydd, were honoured members of Henry VII’s court and virtually ruled much of southern Wales for the next 40 years. The family came to grief in 1531 at the hands of Henry VIII precisely because of its prominence, its pretensions to a lineage that went back to ancient princes and had royal Tudor connecitons, and Henry VIII’s divorce difficulties - in fact Gruffydd’s son Rhys, was King Henry’s first spectacular victim on the eve of the Reformation. His decendants spent the rest of the 16th and the early part of the 17th century trying to rehabilitate the family and repair their fortunes. The 17th century Life of Sir Rhys ap Thomas has not been published since 1986 and is here edited in full: it forms the second part of a study that is a contribution to the understanding of the Wars of the Roses and the political developments in England, Wales and France during the early Tudor period.