BMedSci Sheffield 1986, MB ChB 1987; MRCP UK 1991; MRCPath 1996; MD Sheffield 1997.
After qualifying, Chadwick held house positions at Gwynedd District General Hospital and Monsall Hospital. From 1991 to 1997 Chadwick was registrar and senior registrar in medical microbiology for the North West Regional Health Authority. In 1997 he was appointed consultant in medical microbiology for Salford Royal Hospitals NHS Trust. Chadwick published a number of articles on the epidemiology of hospital acquired infections.