Epidemiology requires large-scale, high-resolution, representative population data sets; data extracted from electronic health record systems meets these criteria. However, within the UK, there is no single electronic health record, and the record of a patient's healthcare is fragmented over multiple systems and multiple organizations. In the SHORE project we have developed a proof of concept system that addresses these problems by retaining control of patient data at a local level, where it can be effectively interpreted and governed, and by overlaying on these data sources privacy-preserving record linkage providing a unified view of the health and care of the population.