Leslie McLoughlin was born on 24 February 1935. After studying history at Manchester University, McLoughlin spent two years in National Service as an instructor officer in the Army Educational Corps (1955-57). At the direction of the Army he returned to university, at Durham, to learn Arabic (1960-61), and joined the Middle East Centre for Arab Studies (MECAS) in 1961. After a spell teaching Arabic to British forces in Aden [Yemen] between 1962 and 1964, McLoughlin became Principal Instructor at MECAS from 1965 to 1968.

For a short time, McLoughlin taught Arabic outside MECAS, first at Edinburgh University [Scotland] between 1969 and 1970, and also as a visiting professor at the University of Pennsylvania [United States] in the summer of 1969, then at Columbia University in 1970. He then returned to MECAS once again, remaining there between 1970 and 1975. McLoughlin's other duties have included acting as a Foreign Office and Ministry of Defence interpreter from 1983 onwards, and he is also a Fellow of the Institute of Arabic and Islamic Studies.