Jack Middleton got his first taste of competitive swimming in 1932 at the age of 15, when he competed in the Warwickshire Junior Championships. He went on to become one of the Midlands’ top male swimmers in the 1930s, and was one of the leading British backstroke swimmers of that decade. He was also a good standard water polo player. Middleton qualified for the 1936 Berlin Olympics after finishing second to Jack Besford in both the Olympic trial and ASA Championships. It was his one and only ASA podium finish. Unfortunately, at the Berlin Games, Middleton finished fifth in his 100 metres heat, and failed to qualify for the final. He could well have qualified for the cancelled 1940 Olympics; instead, he saw service with the Royal Navy in World War II. After the War, he returned to swimming and continued winning Warwickshire County titles and, beyond the age of 30, was captain of the Warwickshire county water polo team.