The prominence of religious issues in eighteenth-century British politics has received growing, and gratifying, recognition in recent years. In particular, attacks upon, and defences of, the doctrine of the Trinity have been seen as central to theological, and hence to political, debate. For many, the term ‘orthodoxy’ without qualification referred to one's position on this question. Although there is perhaps still insufficient emphasis upon trinitarian orthodoxy as a central feature of what is fashionably termed the state's self-image, Unitarianism is rightly perceived as important to critiques of the existing regime, especially after 1750. Historians of the Wilkites, of later eighteenth-century radicalism and of peace campaigns in the Napoleonic period, have cast Unitarians in at least a supporting, and sometimes a leading, role. Yet too often Unitarianism has appeared elusive and difficult to pin down, manyheaded and half-concealed under the vague label of ‘heterodoxy’.