This thesis examines continuity and change and the role of trade unions in state industrial relations policy in Britain in the period 1910-21. Contrary to orthodox interpretations which point to a watershed during World War 1, it is argued that state industrial relations policy remained remarkably consistent in this period. To a significant extent this consistency was due to the scale and character of worker organisation. The influence of syndicalism and industrial unionism added a new and threatening dimension to worker organisation because of the emphasis these movements placed on empowering the rank and file rather than trade union leaders. This shift was perceived as a threat to the national interest- which forced the state to intervene but limited the forms which intervention could take. The form of intervention with the fewest repercussions was conciliation which involved the promotion of "responsible" trade unionism. This policy was based on the idea that responsibly led trade unions acted as a discipline and control on their members. They could prevent industrial conflict from reaching the point where repressive state intervention became inevitable. This view of trade union leadership is a central theme in an influential body of literature in industrial relations known as "rank and filism". The thesis highlights the problems with this approach between 1910 and 1921 notably that the actions of trade union leaders' were less significant than those of the rank and file. It argues for a more sophisticated and qualified version of rank and filism.