This is a new edition of the authoritative study of the family of Sir Rhys ap Thomas in the fifteenth and sixteenth centuries. It places the family in the social and political context of Anglo-Welsh history: the turbulent career of Gruffydd ap Nicholas of Newton (Carmarthenshire) and his sons during the Wars of the Roses, the crucial importance of Rhys ap Thomas to the establishment of the new Tudor dynasty in both Wales and England; the close relationship between Sir Gruffudd ap Rhys and Prince Arthur, and the execution for treason of Sir Gruffudd's son in 1531 which crippled the family for two generations. A new introduction reviews aspects of the Wars of the Roses in Wales and the impact that the new Tudor dynasty had on the relationship between England Wales after 1485.