This thesis is about organizations working in the field of British civil liberties between 1934 and 1989. It examines the relationship between the concepts of civil liberties and human rights within a British context, and discusses the forms of political activism that have accompanied this subject. At the centre of this work is an examination of the politics of the National Council for Civil Liberties (NCCL), an organization that has played a key role in the protection and promotion of civil liberties from its formation in 1934. It also examines the activities of a range of other organizations that considered themselves to be active on such a subject. The thesis argues that thinking about civil liberties has been extended throughout the twentieth century to incorporate a more positive and broader conceptualization of rights. However, for all the increased importance of the politics of human rights, a tradition of civil liberties has remained crucial to organizations working within such a field. The thesis also seeks to demonstrate that concerns about civil liberties have often reflected the political ideologies of those acting on such issues. Whilst a large amount of conceptual agreement has existed over the importance of the subject within Britain, this has consistently been met with disagreement over what this means. NGOs have played crucial roles as mediators of such a conflict. In performing such a role, the civil liberties lobby has been characterised by a set of professional, expert activists that have, at times, been able and will to engage with radical political ideas.