Following the appointment of its first aristocratic Grand Masters in the 1720s and in the wake of its connections to the scientific Enlightenment, ‘Free and Accepted’ Masonry rapidly became part of Britain’s national profile and the largest and arguably the most influential of Britain’s extensive clubs and societies. The new organisation did not evolve naturally from the mediaeval guilds and religious orders that pre-dated it, but was reconfigured radically by a largely self-appointed inner core. Freemasonry became a vehicle for the expression and transmission of the political and religious views of those at its centre, and for the scientific Enlightenment concepts that they championed. The ‘Craft’ also offered a channel through which many sought to realise personal aspirations: social, intellectual and financial. Through an examination of relevant primary and secondary documentary evidence, this thesis seeks to contribute to a broader understanding of contemporary English political and social culture, and to explore the manner in which Freemasonry became a mechanism that promoted the interests of the Hanoverian establishment and connected and bound a number of élite metropolitan and provincial figures. A range of networks centred on the aristocracy, parliament, the magistracy and the learned and professional societies are studied, and key individuals instrumental in spreading and consolidating the Masonic message identified. The thesis also explores the role of Freemasonry in the development of the scientific Enlightenment. The evidence suggests that Freemasonry should be recognised not only as the most prominent of the many eighteenth century fraternal organisations, but also as a significant cultural vector and a compelling component of the social, economic, scientific and political transformation then in progress.