Barrett's life, friendships and dual careers as an historian and minister in the Methodist church are comprehensively recorded in the papers. After completing his doctoral thesis on the religious aspects of colonial life, his research interests focused on the social history of war in Australia, including conscription. Through his academic work Barrett established contacts with many prominent historians, and numbering amongst the correspondents are Russel Ward, Hugh Stretton, Douglas Pike, Manning Clark, Allan Martin, Roger Joyce, John Hirst, Ken Inglis, Peter Cook, Sir Keith Hancock, W.W. Phillips, Leonie Foster and Inga Clendinnen. Collectively the letters reveal much about 20th century Australian historiography, as well as the politics of university history departments.