L. F. Fitzhardinge was educated at Sydney Grammar Schoool, the University of Sydney and New College, Oxford. He gained a BA (Hons.) in Greek and Latin from Sydney, another BA (Hons.), this time in Classics, from Oxford and also a B. Litt. from Oxford.
On returning to Australia in 1934, Fitzhardinge was appointed as a research officer at the National Library (at that time still a part of the Parliamentary Library). He became Reader in the Sources of Australian History in 1951 and soon after began a major work on Billy Hughes. (He completed the biography some 20 years later.)
In 1983 Fitzhardinge was elected a Fellow of the Australian Academy of the Humanities and in 1987 a Fellow of the Royal Australian Historical Society.
