This work investigates the political influence and administrative role of Aymer de Valence, Earl of Pembroke, during the tumultuous reign of King Edward II. J.R.S. Phillips, a distinguished historian of medieval Britain, utilizes extensive archival research and primary source documentation to reconstruct the Earl's career. The book argues that Pembroke acted as a critical, often moderating, force within the fractured baronial politics of the early fourteenth century, providing a necessary counterpoint to the more radical factions of the era.

Historians regard this text as a definitive biographical study of a pivotal yet often overlooked figure in medieval English politics. Readers frequently note the academic density of the prose, which provides a rigorous examination of baronial governance and diplomatic maneuvering.