This chapter reflects on the UK’s use of proscription, and the implications of this for our knowledge of national security today. The historical and relational contexts explored in the book demonstrate – we argue – the ongoing relevance of proscription, and particularly the international influence of the UK’s proscription traditions, in shaping state administration. The multiple functions assigned to this power, moreover, also exposes proscription as a versatile tool of political convenience for regulating ideas and, in particular, political symbols. Here we suggest that central to proscription is the British state’s preoccupation with symbolic power, whether displayed through the flying of flags, the wearing of uniforms, the performance of rituals or the recitations of oaths. On this analysis, proscription is concerned with denying symbolism to illegitimate entities even though, or perhaps because, citizenship itself is a symbolically constituted status. This sensitivity to rituals, we argue, has wider implications for security scholars insofar as it potentially renders visible other security moves by state institutions, and for our understanding of the political more broadly.