This article examines the articulation and reflection of Britishness by leaders and members of the Campaign for Nuclear Disarmament (CND) in the 1960s. Members of CND believed that Britain had a distinctive world role which was founded on, and informed by, their morality. This morality, like the British character it helped to define, was not static but ever changing. CND was thus not simply reflecting existing ideas and attitudes to Britishness—although it did do this particularly in relation to domestic British values—but also wanted to be at the forefront in helping to define what British morality should be. CND thus articulated a Britishness that was both domestically conservative and internationally progressive. This article explores how attitudes towards Britain’s international role and the domestic identity of Britons informed one another through CND's conception of a uniquely British morality.