The Norman conquest of England in 1066 created a cross-Channel baronage whose personal interests in Normandy and England were an important influence on their subsequent political activities during the reigns of the Norman king-dukes. While there has been extensive scholarship on this theme prior to 1154, there has been only limited research in the later twelfth century, when the Plantagenets ruled both countries. Most modern assessments of baronial motives and behaviour during the latter period assume their cross-Channel interests had diminished, becoming less influential on their ambitions and actions, and contributing to the loss of Normandy in 1204.

The purpose of this thesis is to test the validity of these conclusions through a study of the baronial families of two specific areas, the Pays de Caux and Cotentin, between 1189 and 1204. The extent of their commitment to maintaining the cross-Channel connection is determined through a detailed analysis of their cross-Channel interests and activities, based primarily on the evidence provided by their own charters, and the increasingly abundant records of the Plantagenet administration. The two regions presented their barons with different circumstances and challenges. In the Pays de Caux significant cross-Channel interests were largely confined to a small number of very rich barons, whereas in the Cotentin they were distributed more extensively across many lesser families. Similarly, the two regions were exposed to different external influences: the Pays de Caux was increasingly vulnerable to the expanding influence of the king of France, whereas the barons of the Cotentin continued to maintain their traditional connections with the cross-border families of the Norman-Breton frontier. The barons of these two regions have been little studied previously, in contrast to those of the frontier regions of Normandy, especially by Daniel Power, and hence the thesis provides a fresh perspective on the barons of Normandy during the reigns of the final two Plantagenet king-dukes.

The thesis consists of an introduction, including a survey of the historiography and sources, a main body of four parts each divided into two chapters, a conclusion and appendices, including genealogies of selected families. The first two parts examine the personal stake of individual barons in both countries through an analysis of the distribution and evolution of their cross-Channel landholdings, and their participation in social networks within local aristocratic communities in Normandy and England. This understanding of where barons focused their ambitions, whether in one country or on both sides of the Channel, informs the assessment in parts III and IV of their political interest in maintaining the Anglo-Norman realm as reflected in their military service in Normandy and loyalty to the Plantagenet king-dukes. The analysis reveals that by the end of the twelfth century these cross-Channel interests remained of vital importance to the baronial families and underpinned the consistent loyalty shown by most to the Plantagenet rulers. This close alignment with the king-dukes encouraged many families to extend their cross-Channel interests in this period, further strengthening their commitment to the Anglo-Norman realm.