He was educated at Birkenhead School and St John's College, Cambridge, where he gained firsts in Part I of the Classical tripos and Part II of the Historical tripos prior to completing a PhD in 1950.
[1] He began his career as a fellow at Queen's College, Oxford, where he remained until his return to St John's in 1966.
[1] He was Reader in British History at Cambridge from 1976 to 1980, at which point he decided to retire from university teaching.
Doing so, however, led St John's to terminate his college fellowship as well, much to his chagrin, and it was only after a great deal of protest that he was reinstated (an interregnum he referred to thereafter as socius ejectus, in imitation of Thomas Baker).
[1] Pelling's collection of British left-wing political pamphlets is held at Senate House Library, while his papers are lodged with St John's College.