From October 2008 until January 2017, he served as the Dean of Medicine and the Head of the Medical Sciences Division, University of Oxford.
During ten years in Calgary, Buchan built up a team which established a fully comprehensive regional Stroke Programme and led large multi-centre studies CASES, ASPECTS and FASTER.
When he returned to Oxford in 2005, he left Calgary with an Acute Stroke Imaging Centre, an Experimental Imaging Centre and the Clinical Stroke Programme, which facilitate translation of the experimental research work in the laboratory to the clinical setting.
He also led the Oxford University bid for a Wellcome Clinical Research facility and successfully obtained funding for the new Acute Vascular Imaging Centre (AVIC).
At the same time, he was charged with the task of heading the John Radcliffe Hospital Division of the Nuffield Department of Medicine.