This book takes a fresh look at British radicalism in the first half of the nineteenth century from the perspective of the new and burgeoning field of the history of emotions. By studying the affective leadership of radical leaders, and the use as well as abuse of feelings for political causes, this book aims to change the way in which we look not only at the leaders in question and the movements that grew up around them, but at the affective qualities of politics itself. This study represents a major challenge to the ways in which historians have studied political culture in modern Britain by showing how we must break away from teleological assumptions about the rise of rationality. Politics did not just revolve around ideas, power, organisation and practice but also feeling. It raises questions fundamental to politics in every age: should the public sphere be a domain free from feeling, or at least one where restraint is exercised? What are the consequences for democratic polities where either affective restraint, or its opposite, excess, operates? How do public displays of feeling complicate our understanding of the historic and gendered separation of public and private? Are there occasions when public displays of feeling are acceptable (or less acceptable), and, if so, when and why?