Throughout its history, internal conflict has divided and threatened to rupture the British Labour Party. Yet even by the standards of a party accustomed to internal dissension, conflict during the period 1951-59 was particularly intense. It becomes the purpose of the thesis to consider the sources and nature of conflict during the period, and in particular to examine the character of the Bevan/Gaitskell relationship relative to that conflict. It was found that Bevan and Gaitskell were both intellectuals and advanced theoreticians whose analyses led them to adopt different if not always opposing policy positions. On occasions these differences heightened the rivalry between them, and provoked conflict. However, Bevan in particular was willing to restrain his radical, fundamentalist insticts in the interests of preserving party unity. He was also prepared, on occasions, to attempt the influence of policy development not through rebellion, but rather as a participating member of the party leadership group. Just as it is possible to overestimate the importance of ideological difference as a source of conlict between the two men, so too the importance of rivalry between them for power and position is easily overestimated. The research indicates that conflict within the party was created not so much by direct rivalry between Bevan and Gaitskell as by the reaction of Gaitskell, Morrison and most particularly the trade union leadership to the threat posed by organized Bevanism, and by the subsequent reaction and interaction of the fundamentalist and social democratic associates of Bevan and Gaitskell.