[1] He was born in London and educated at King Alfred's School, Hampstead, before being evacuated to Canada and Australia because of the Second World War.
[2] He read Philosophy, Politics and Economics at St Catherine's College, Oxford, after he won an ex-servicemen's scholarship.
[1][2] It was here, with Kenneth Alexander and John Hughes, that he founded day-release educational courses for miners from Derbyshire and Yorkshire.
[1] Harrison also represented the National Union of Public Employees on Sheffield's trades and labour council.
[1] In 1965 he was appointed senior lecturer at Bernard Crick's Department of Political Theory and Institutions at Sheffield before he became reader in 1969.