In this case study, we focus on our recent large-scale quantitative analysis of 9,042 children who accessed sexual exploitation support services provided by a major UK charity. In doing so, our aim is to discuss the practicalities of one important but often neglected source of data for research into child sexual exploitation: data that are routinely generated and collected by non-academic institutions in the course of their everyday business activities. There are considerable practical, logistical, and ethical benefits to using such secondary data. Child sexual exploitation is a highly sensitive and largely hidden issue that is notoriously difficult to research. Consequently, we benefitted greatly from the unobtrusive approach, increased reach, and cost-effectiveness that our research design permitted. Nonetheless, there can also be substantial challenges associated with working with secondary data not generated for research purposes. Among the key barriers we encountered were lack of clarity around key terms and fundamental parameters, missing data, and difficulties finding appropriate baselines against which to interpret our results. We will discuss approaches we took to mitigate these challenges and to ensure high-quality research outputs. Finally, we will reflect on some more general lessons both for the providers and for the users of non-research-oriented secondary data. Their application, we contend, could help ensure more effective research collaborations in future.