During World War II he served in the British Army as a captain in the 17th (Uganda) Battalion of the King's African Rifles.
John Harrison's autobiography (Scholarship Boy: A Personal History of the Mid-Twentieth Century, 1995) is informative about not only the author's academic career but also life in prewar Leicester and military service with the King's African Rifles.
For his 75th birthday his lifetime's work was celebrated by his colleagues with a festschrift: This original collection of critical essays on issues of eighteenth- and nineteenth-century rural life, popular politics and beliefs brought together fifteen well-known historians.
Other essays addressed Owenism, Chartism, the Chartist Land Plan, gender and autobiography, vegetarianism and popular journalism.
There were critical evaluations of the influence of America on British radicalism and socialism, on the motives that drove workers' children to become teachers, and on the construction of images of English rural life.