Concerns about youth violence and the radicalisation of pupils have contributed to the deployment of onsite police officers in schools in England. Little is known about the work these officers do. This article firstly outlines the policy background that led to police in schools, and then, with a focus on the schools in London that have onsite officers, data obtained from a Freedom of Information request are combined with school characteristics data to show that officers are more likely to be based in schools with high levels of pupils from disadvantaged backgrounds. Foucault's work on surveillance is explored in theorising police presence on school sites. The relevance of Agamben's "State of Exception" is examined in relation to the school-to-prison pipeline in the United States. The article highlights the need for more empirical work in schools to research the impact of onsite police.