[3] During World War II, Sergeant served as a lieutenant in the Royal Naval Volunteer Reserve (RNVR) from 1945 to 1948, where he was stationed on corvettes.
[2][3] After his military service, Sergeant joined Mullens & Co. a stockbroking firm and the official government broker in the bond market, with assistance from his aunt.
His transition to journalism occurred after meeting Oscar Hobson, the City editor of the News Chronicle which he joined as a reporter in 1948.
[3] His writing led to a regular column on his travels in the Soviet Union, which was later expanded into the book Another Road to Samarkand (1955).
[5] Sergeant authored several financial publications, including Money Matters (1967) and The Inflation Fighters Handbook (1976).