Despite recent calls for ‘ordinary’ citizens to become active and responsible as individuals in preventing and countering terrorism and radicalisation in the United Kingdom, little is yet known about how members of the general public make sense of political violence, or about how they think it should be dealt with. Using a bottom-up vernacular security studies approach, this article examines what lay citizens believe about the causes of terrorism and what responses they think are appropriate. Based on qualitative data from one-to-one interviews with members of the public and an analysis based on constructivist grounded theory methodology, the article discusses three key figures that emerged from interviewees’ accounts of terrorism: the vulnerable subject, the radicalised individual and the radicaliser. Overall, the results reveal that a radicalisation framework is dominant in participants’ discourses on terrorism. The article argues that the dominant imaginaries of terrorism identified in this research draw consent towards pre-emptive security practices such as the Prevent duty and de-radicalisation interventions. The discussion problematises the depoliticisation of political violence and the normalisation of illiberal security measures that this conceptualisation of terrorism entails, while stressing the discriminatory character of the social imaginaries of terrorism.