A chief petty officer in the Royal Navy, Harry Cullum represented the Navy at Bisley for many years and in 1962 won the national 0.22 pistol title. The previous year he finished joint second in the Duke of Cambridge trophy, shot at a target from 900 yards (823 metres). In 1969, Cullum won the free pistol shooting championship at the South African Games at Bloemfontein, and in 1972 took part in the free pistol 50 metres event at his second Olympics, having competed at Tokyo eight years earlier. Cullum later became a national shooting coach.