Professor Sir John Armstrong Muir Gray CBE FRCPSGlas FCLIP is a British physician, who has held senior positions in screening, public health, information management. and value in healthcare. He is currently the Chief Knowledge Officer for EXi, a digital health therapeutic prescribing exercise to people with or at risk of up to 23 long-term health conditions.

He was director of Research and Development for Anglia and Oxford Regional Health Authority and supported the United Kingdom Centre of the Cochrane Collaboration in promoting evidence-based medicine. He held the positions of director at the UK National Screening Committee, during which he helped pioneer Britain’s breast and cervical cancer screening programmes, and National Library for Health, and director of Clinical Knowledge Process and Safety for the NHS National Programme for IT.