After graduating from Cambridge with a double first, and having won several classics prizes, including the Porson Prize and the Browne Medal, Powell stayed on at Trinity College as a fellow, spending much of his time studying ancient manuscripts in Latin and producing academic works in Greek and Welsh. In 1937, he was appointed Professor of Greek at the University of Sydney aged 25 (failing in his aim of beating Nietzsche's record of becoming a professor at 24). Among his students was future Prime Minister of Australia Gough Whitlam, who described his lectures as 'dry as dust'. He revised Stuart-Jones's edition of Thucydides' "Historiae" for the Oxford University Press in 1938, and his most lasting contribution to classical scholarship was his "Lexicon to Herodotus", published the same year.