 After attending Abbotsholme School in Rocester between the ages of 10 and 17, Unwin started working as a book salesman for Basil Blackwell, whose father was the founder of Blackwell's bookshop in Oxford.Between 1944 and 1947, he served in East Asia as a sub-lieutenant in the Royal Naval Volunteer Reserve.He then studied for an undergraduate degree at Trinity College, Oxford, before completing a master's degree in English at Harvard University, which he attended as a Fulbright scholar.