John W. Long was born in Southampton, England, on May 8, 1921. He grew up in London and at the age of 17 he was offered a trial with Brentford.
During the Second World War Jack served in the Army with the Hampshire Regiment. During the war he guested as a player with Chester City. He made one appearance as a fullback in the Football League for Exeter City in the 1946-47 season.
After the war Jack had qualified as a Football Association coach. In the summers of 1947 and 1948 he coached the Larvik Turn club in Norway. He was said to have been offered a ten year contract in Norway and also to have been offered a contract with the Malta Football Association.
Playing at fullback Jack was the captain of Boston United in the 1947-48 and 1948-49 seasons.
In the 1949-1950 season he was the player manager of Ilfracombe Town in the Western League.
Jack emigrated to Canada in October 1950 and joined Toronto club Ulster United. In the 1951 season he helped Ulster United win the Dominion Championship. Jack left the Redhanders after the 1953 season.