Matthew Smallman-Raynor and Andrew Cliff are Professors of Geography at Nottingham and Cambridge Universities. With Peter Haggett at the University of Bristol, they have led an interdisciplinary research group for over a quarter of a century which has worked upon the spatial diffusion of infectious diseases. Special focuses for the group have been reconstructing the processes by which diseases move from one geographical region to another, understanding the causes of epidemic waxing and waning in time and space, and the demographic consequences of disease. Together, they have written twenty research monographs and 100 scientific papers on these topics.