Auchmuty was born in Portadown, County Armagh, Ireland, the elder son of James Wilson Auchmuty, a Church of Ireland clergyman, and his wife Annie Todd (née Johnston). James Johnston Auchmuty graduated from Trinity College, Dublin (BA, 1931; MA, 1934; Ph.D., 1935). He was elected auditor of the College Historical Society for 1931-32. Auchmuty was schoolmaster at Sandford Park School from 1934 to 1936 and lectured in education at Trinity College 1938 to 1943.
MI6 and Egypt
Due to poor eyesight Auchmuty was unable to join the armed forces, however he was recruited by MI6 and performed intelligence work and pro-British cultural propaganda in Ireland. Auchmuty decided to leave Ireland after World War II to avoid being interred for working on non-Irish interests. He then worked as and associate professor of history at Farouk I University at Alexandria, Egypt teaching and continuing his work of political reporting and propaganda until the overthrow of King Farouk in 1952. 
Career in Australia
British intelligence contacts then found Auchmuty a position as senior lecturer in history at the New South Wales University of Technology, Sydney (later the University of New South Wales) where he moved later in 1952. He was no longer an intelligence operative. In 1954 Philip Baxter, the university’s director, sent Auchmuty, as associate professor, to head the school of humanities and social sciences at Newcastle University College. In 1955 he was promoted to professor of history and deputy-warden of the University College, becoming warden in 1960 and foundation vice-chancellor when the college gained autonomy as the University of Newcastle in 1965.
Awards and memberships
Auchmuty was elected as a fellow of the Royal Historical Society in 1938. He was a foundation member (1956) and chairman (1962 to 1965) of the Australian Humanities Research Council and a foundation fellow (1969) and member (1969-70) of the council of its successor, the Australian Academy of the Humanities. Active in the Australian Vice-Chancellors’ Committee (chairman, 1969-71), Auchmuty was also a council member (1967 to 1974) of the Association of Commonwealth Universities and was awarded its Symons medal in 1974. From 1973 to 1976 he chaired the Australian National Commission for the United Nations Educational, Scientific and Cultural Organization. He was appointed CBE in 1971 and in 1974 was awarded honorary degrees by the universities of Sydney (D.Litt.), Newcastle (D.Litt.), and Trinity College, Dublin (LL D). On retirement from the University of Newcastle in 1974, the library and the sports centre were named after him, in honour of two of his particular interests. He and his wife then moved to Canberra.
- Photograph "Professor — James Auchmuty at the University of Newcastle, Australia"
- Photograph — "James Auchmuty with R.G. Keats and B.H. Neumann" taken September 1974
- Dutton, Kenneth R. "Auchmuty, James Johnston (1909–1981)". Australian Dictionary of Biography. Canberra: Australian National University. Retrieved 3 August 2012.
- "Honorary awards - Senate - The University of Sydney". Retrieved 5 August 2012.
- Kenneth R Dutton, Auchmuty: The life of James Johnston Auchmuty (1909-1981), Brisbane: Boombana Publications, 2000, ISBN 1-876542-05-5