Garth Manton was active in rowing in the aftermath of World War II and had his greatest success in the mid-1950s, winning Australian Interstate Championships in the eights in 1954 and 1956 and coming in second in 1955. He was selected to represent his country in the eights at the 1956 Melbourne Olympics, where the Australians took home the bronze medal. A member of the Mercantile Rowing Club, he was involved in the administration of his sport at several clubs after his retirement from active competition and was inducted into the Victorian Rowing Hall of Fame in 2010 for his contributions.
Australia