This thesis posits that in the post World War 2 era, a nexus of relationships has given rise to a transnational group of five states that form a Deutschian security community. This Anglospheric security community of the US, UK, Australia and NZ, is examined by utilising Adler and Barnett’s security community model. The model is adapted to give greater weight to the role of memes/culture. It finds that it is culture factors (meme-complexes) related to political values and social behaviour that inform the nature, and modus operandi of this Anglospheric security community. The Brexit debate on the UK’s future is found to have illuminated these issues by exposing aspects the contradictions between the competing meme-complexes of the wider Anglospheric community and the EU.

The Anglospheric security community’s durability and progress is found to be directly related to notions of legitimacy. This conclusion is informed by revisiting Deutsch’s original writings on the difference between naturally developing communities and the dangers of policy-elites creating political constructs that run counter to cultural considerations. A values-based meme-complex found to provides not just a common identity but to inform the nature of the Anglospheric security community from which it accrues legitimacy.

It is further posited that the Adler and Barnett model’s standard categorisations of pluralistic security community types do not adequately describe certain features of the Anglospheric security community. The research in this thesis has uncovered new institutions and fora and established that members do assist one another in conflict and confirms it to be a tightly-coupled version. However, the Anglospheric security community displays an actorship not implicit in Adler and Barnett’s categorisation. This thesis offers the terms ‘synergic’ and ‘hemiplegic’ to describe functional and dysfunctional communities. The Anglospheric security community is held to be synergic since it exhibits actorship on defence and security matters externally. In contrast the European Union is held up to be hemiplegic due to endemic problems to function cohesively on external defence issues.