John read Human Sciences at Hertford (1972-5) before moving to Cambridge to undertake graduate work in historical demography at the Cambridge Group for the History of Population and Social Structure.
After a year as a demand analyst with the planning division of Shell UK Ltd he joined the Anthropology Department of University College London as a Lecturer in Biological Anthropology. In 1991 he returned to Oxford as a University Lecturer in Historical Demgraphy and Fellow of All Souls College.
From 2005 to 2011 he was Principal of Hertford College where he is now a Senior Research Fellow.
John’s doctoral research was on the demography of eighteenth century London. Further research on the problem of London’s mortality in this period led to the publication of Death and the Metropolis in 1993. His principal research interest has been in the dynamics of infectious disease mortality in the period before the development of effective medical interventions. His work has focussed on the problem of how mortality change related to social and economic change, particularly urbanisation, and more recently the effects of war.