[3] After National Service, he was elected a prize fellow of Magdalen College, Oxford, where he completed a doctoral thesis on the Italian republic set up during the time of Napoleon Bonaparte.

[3] Roberts did not hesitate to take on ambitious subjects, and in 1976 he published The History of the World, regularly updated in later years and still in print today.

[4] The Times Literary Supplement described Roberts as "master of the broad brush-stroke", and in 1985 Roberts wrote and presented the thirteen-part BBC television series The Triumph of the West, a series which painted a broad canvas but avoided simplistic solutions, encouraging the audience to think and reach its own conclusions.

The John Roberts Memorial Fund was established in his honour at Merton College in 2003, with the aim of increasing the financial support available to undergraduate and graduate students.

At Oxford on 29 August 1964 Roberts married Judith Cecilia Mary Armitage, a schoolteacher, and they had one son and two daughters.