Professor Harrison is the National Police Chief Medical Officer for England and Wales in the College of Policing. Previously, he was Chief Medical Officer for Devon and Cornwall Police and strategic health and wellbeing lead for the Alliance with Dorset Police. He was Clinical Director of Organisational Health and Wellbeing at Imperial College Healthcare NHS Trust (2003 - 2014) and Senior Lecturer in Occupational Medicine / Consultant Occupational Physician at the University of Newcastle-Upon-Tyne (1990 - 2003). He is an Associate Professor at Brunel University in clinical organisational development. Previously he was Academic Dean of the Faculty of Occupational Medicine.