For the last 10 years Marion has been a senior researcher leading large randomised trials in diabetes and cardiovascular disease at the Nuffield Department of Population Health (NDPH) at the University of Oxford. During this time she has developed new trial methods, including use of routinely collected healthcare data in trials. Since 2020 she has lead the data linkage team for the RECOVERY trial. She is a member of several trial steering committees and co-leads the Health Data Research UK clinical trials programme.