This comparative and historical project, covering the period 1974-2007, is focused on two eras of political violence in Britain, the first coinciding with the Irish ‘Troubles’ and the second since 2001.The research examined to what extent and in what ways Irish communities and Muslim communities were represented as ‘suspect’ in public discourse in these two eras, it examined the similarities and differences in the impact of these representations and counter-terrorism measures on Muslim communities and Irish communities in Britain. Our aim was to explore the implications for social cohesion of representing some groups as ‘suspect’ and what lessons can be learnt from evolving understandings of and responses to national security threats. The research provides a new analysis of Irish experiences and compares this with current Muslim experiences. Our critical assessment of British counter-terrorism policies over four decades offers useful insights to policy-makers who seek ways to implement counter-terrorism policies without alienating communities.This report highlights the main findings of our research.