John McGhie received his education at the famous Hamilton Academy school from which he matriculated at the University of Glasgow, graduating in medicine in 1936.
Posted to India in 1938, he was subsequently appointed Medical Officer at the British Military Hospital at Rawalpindi and served in the Burma Campaign from 1942 to 1945, commanding 47 Field Ambulance.
For the next nine years McGhie worked at the Royal Victoria Hospital at Netley as Officer in Charge, Psychiatric Division, and latterly as Officer Commanding the hospital and in 1961 he was appointed Director of Army Psychiatry in the Royal Army Medical College.
In 1967 McGhie took up the appointment as deputy director of Medical Services in the Malaya and Western Commands before returning, in 1970, to the post of Director of Army Psychiatry as well as being appointed Consultant Psychiatrist to the British Army, with the rank of Major-General.
Retiring from the Army in 1976, John McGhie continued work as a consultant psychiatrist to government bodies and was appointed President of the Ministry of Defence Army Medical Board, finally retiring in the year of his death, dying at Lenham, Kent, on 12 September 1985.