 Next he was appointed Reader in Microbiology at the National Heart and Lung Institute, where his interests turned to the immunology and epidemiology of tuberculosis.From there he became assistant lecturer (1969-1970) at the "Bland Sutton Institute of Pathology" of "Middlesex Hospital Medical School", University of London and then lecturer in the same school's "Department of Microbiology" from 1971 to 1976.From 1976 to 2000, Grange was Reader in Clinical Microbiology at the Imperial College School of Medicine and honorary consultant Microbiologist to the Royal Brompton NHS Trust.