In a 2017 speech to the United Nations, Theresa May referred to the UK’s ‘special responsibilities’. This article examines how the UK can properly discharge those responsibilities at the UN in ways that defend its claim to be a permanent member. We offer an innovative analytical framework that merges English School theory of international society with diplomatic practice theory, and find that there are limits to the claim that the UK compensates for its relative material decline through diplomatic activism. We identify the special responsibility of the permanent member in terms of a capacity to reconcile the ‘concert’ and ‘governance’ functions of the Council, and to contribute materially to the achievement of governance objectives in areas where consensus is possible. Drawing on extensive interview data, and illustrating with reference to current debates on peacekeeping, we find that the an ongoing UK capacity to ‘punch above its weight’ diplomatically is dependent on an increased material commitments and to a more inclusive
approach in the Council.