He published many books about Yemen and Arabia as well as about French and British colonial history.
From 1955 to 1959 he served as Political officer in Western Aden Protectorate in the hinterland of present-day Yemen.
In 1965 he returned to Cambridge University where he earned his PhD in 1968 about the French administration in Morocco.
Between 1968 and 1990 he had been Secretary and Librarian of the Middle East Centre in the Faculty of Oriental Studies in the University of Cambridge.
From 1980 on he dedicated the rest of his life to his masterpiece Dictionary of Modern Arab History – An A to Z of over 2,000 entries from 1798 to the present day.