The impact transport has on our physical and mental health and on the environment is increasingly recognised by academics, practitioners and decision-makers. To inform policy-making and research, it is crucial to have access to sufficient comprehensive datasets linking these topics. Large scale surveys rarely ask questions on transport, health and sustainability, yet these limitations are likely to affect research and policy-making. This project set out to identify the gaps in administrative and survey datasets to link health outcomes to travel behaviour and the quality of the environment; investigate the impact this has on research and policy-making; how these gaps might be addressed; and what the needs are for joined datasets. To achieve this, the project interviewed key decision-makers and stakeholders across England, including civil servants within national or local government and third sector organisations. The results highlight gaps within national datasets; the insufficient links between health, transport, and sustainability datasets; and the need for further joined data in various fields, in particular active travel, health and wellbeing. Participants suggested several solutions, including better harmonisation of surveys and data fusion.