BA Manch 1945, MA 1950; MB ChB Edin 1948, PhD 1957, MD 1958; FRCP Edin 1963; MRCP Lond 1969; MRCPath 1963.
After junior hospital appointments and military service, Gardner was appointed research fellow in pathology at the University of Edinburgh in 1954. He became lecturer in 1956 and senior lecturer and honorary consultant pathologist in 1961. During this period he spent a year as research fellow in experimental pathology at the Western Reserve University, Cleveland, Ohio. In 1966 Gardner was appointed director of the Kennedy Institute of Rheumatology and was also consultant pathologist to Charing Cross Hospital Medical School. Gardner was appointed Musgrave Professor of Pathology and director of the Institute of Pathology at Queen's University Belfast in 1971. He was appointed to the newly created chair of histopathology at the University of Manchester in 1976. Gardner retired from the chair in 1988 and returned to Edinburgh to a part-time research fellowship in osteoarticular pathology.