The nexus of mobile technology, mass media, and public engagement is opening new opportunities for research into the human behaviours relevant to the spread of disease. On 22 March 2018, the British Broadcasting Corporation (BBC) released the documentary “Contagion! The BBC Four Pandemic” to describe the science behind pandemic preparedness in the UK. The authors of this article were responsible for producing a mathematical simulation for that documentary of how a highly contagious respiratory pathogen might spread across the UK. According to the documentary narrative, the ‘outbreak’ begins in the town of Haslemere, England. To ground the simulation in true human interaction patterns, a three-day citizen science experiment was conducted during which the pairwise distances between 469 volunteers in Haslemere were tracked continuously using a mobile phone app. Here, we offer a scientific companion to the documentary in which we describe the methods behind our simulation and release the pairwise interpersonal distance dataset. We discuss salient features of the dataset, including daily patterns in the clustering and volatility of interpersonal interactions. Our epidemiological analysis of the simulated Haslemere outbreak serves as a springboard to discuss scientific opportunities opened by the Haslemere dataset and others like it. We believe that the Haslemere dataset will productively challenge current strategies for incorporating population structure into disease transmission models, and hope that it will inspire the collection and analysis of other similar datasets in the future.