The private security industry has become a central feature of the plural policing landscape in the United Kingdom. As such, it has received considerable attention in both academic and policy circles. Yet, perhaps surprisingly, there remain notable question marks over its precise size and shape. With this in mind, the article draws upon data from the Security Industry Authority and the Office of National Statistics Business Register and Employment Survey to measure the sector along three key dimensions: the number of private security officers, the number of companies and turnover. This novel methodological approach reveals a complex and contested picture of what the sector looks like at a fundamental level and, at the same time, allows for a reassessment of commonly deployed indicators such as growth rates and the ratio of private security officers to police officers during key time periods such as the Covid-19 pandemic
