Green's prominence grew in 1930 as he set a new world record while becoming Britain's first national 50 km racewalking champion in July. After a string of victories in other British events, he captured his first international title at the international 100 km race in Milan. His continuing success through 1931 and 1932 earned him a trip to the 1932 Summer Olympics in Los Angeles, where he won a gold medal in the first ever men's 50 km walk at the Games. At the time he was 38 years old and he remains, as of 2008, the oldest person to have won the event. He contested fewer races in 1933 and 1934, but he set his sights on making an appearance at the 1936 Summer Olympics in Berlin and resumed his heavy regimen of training in 1935. He was runner-up to Harold Whitlock for the British 50 km title that year, but he slid to fourth place in the following year's competition and was not selected for the Berlin Games. Whitlock, who captured the 1936 National Championship with a world record time, became the eventual winner of the 1936 Olympic 50 km walk.