This thesis shows that despite the rhetoric of universalism and internationalism used by the Royal Society, especially after the onset of Cold War, its policies and actions in the period 1945-75 remained closely allied to the interests of the British state. More specifically, in its foreign relations the Society mainly operated within a network of Western intergovernmental organisations that were a response to, and operated in similar ways, to Eastern Bloc organisations. While financially dependent on a Parliamentary grant-in-aid, they effectively carved out a role in the sphere of international scientific relations which was built upon an image of independence from the state. Thus, Society Officers and staff were able to mobilise a double-sided discourse of utility to, and independence from, the state. The association between the government of the day and the Society was at its most effective when a consensus existed between like-minded government administrators and Officers of the Society. A culture of collaboration and informal networks allowed them to build relationships and share ideas. The Society was perfectly designed to facilitate this culture, as its Fellows permeated government networks as individuals as much as they did as direct representatives of the Society. The status of Fellows conferred on them eligibility for a variety of positions, both formal and informal, within the elite infrastructure of national life. The thesis also shows that party political and ideological motivations often prefaced associations between Fellows and like-minded politicians or civil servants, but these associations were principally between economic liberals to the exclusion of far left scientists. However, the Society's connections with the government were also motivated by reasons beyond party politics. The Society had an overarching aim to preserve the United Kingdom's position as a scientific 'Mecca'. In the shifting post-war landscape, in which the country became more dependent on outside help and conscious of its relative decline in economic and political power, the Society looked beyond national borders to stay in the competition. The thesis shows that Officers of the Society responded creatively to the changing geopolitical landscape as old spheres of influence waned, such as the Empire-Commonwealth, and new ones opened up, such as the European Community and the special relationship with America. The Society pursued these new opportunities with patriotic ambition, often prioritising relations that promised scientific rather than political gains, but always within a Western framework.