Born in Kensington, Harry Bull played for the Surrey Schoolboys XI before seeing military service in the Middle East. He joined Wimbledon after the Second World War but such was the strength of the side that he had limited first team opportunities and left to join Southall in 1947. He returned after one season and flitted between the two clubs for a couple of seasons, becoming a very useful utility player and appearing in every position including goalkeeper during the early 1950s. In 1955 he left Plough Lane and signed for Leytonstone.