In 2006, Buchan was appointed Director for the NIHR Oxford Biomedical Research Centre, one of the five comprehensive centres. At the same time, he was charged with the task of heading the John Radcliffe Hospital Division of the Nuffield Department of Medicine. He established and chaired the cabinet of the UK Biomedical Research Directors for the other five centres in the country. Appointed Dean and Head of the Medical Sciences Division in 2007, he was instrumental in establishing a number of new departments in the University, including the Nuffield Department of Clinical Neurosciences, the Department of Oncology, the Nuffield Department of Population Health, the Nuffield Department of Primary Health and the Radcliffe Department of Medicine, as well as the Oxford University Hospitals NHS Trust in November 2011. Since then, the medical school/medical sciences division at Oxford has, for seven successive years, held the top ranking worldwide for clinical, pre-clinical and health in the Times Higher Education World University Rankings. In 2005, he has been appointed Governor at Repton School, where he is developing the Repton Science Priory to encourage greater interest in science for the school engaging with local schools, business, and the community. In April 2007 he was made a Fellow of the Academy of Medical Sciences (FMedSci). In his position as Pro-Vice-Chancellor and Head of Brexit Strategy he endeavours to maintain Oxford as the leading European university, one with global reach. He has brokered partnerships with the Universities and hospitals in Berlin to build a Centre for Oxford in Berlin, the Oxford in Berlin Research Centre, and a complementary Berliner Haus for the Berlin Universities in Oxford.