A scholarship student at the Manchester Grammar School, Kiernan developed a passion for the classics, as he added ancient Greek and Latin to the modern European languages he had already learned at home. Propelled with three new scholarships, he went on to Trinity College, Cambridge where he achieved a double-starred First in History (B.A.,1934; M.A., 1937). Recruited by Guy Burgess during a time of radical ferment among Cambridge students, Kiernan joined the Communist Party in 1934. He found his radicalism subsequently reinforced by what he regarded as the treachery of Britain's elites. Perhaps the greatest influence on Kiernan was Maurice Dobb: a lecturer in economics at Cambridge, Dobb had joined the Communist Party of Great Britain in 1920 and was open with his students about his communist beliefs. Kiernan later wrote: "We had no time then to assimilate Marxist theory more than very roughly; it was only beginning to take root in England, although it had one remarkable expounder at Cambridge in Maurice Dobb."