He is the former director the Oxford Dictionary of National Biography (2004 to 2014) and of the Institute of Historical Research (2014 to 2017), University of London.

Upon graduation he received a Harkness Fellowship, which enabled him to study history of slavery and American Civil War at Yale University for a year with Ed Morgan, David Montgomery and David Brion Davis.

He continues to teach regular adult classes and is president of the Thames and Solent district of the Workers' Educational Association.

In 1990, he was appointed to a Fellowship at St Peter's College, where he has also served as admissions tutor and senior dean.

[3] During the academic year 2000–01, he was the university assessor, a senior administrator responsible for student welfare.