At the Mexico City Olympics in 1968, Hemery won the 400m hurdles in 48.12 seconds, a new world record. His margin of victory was the largest since 1924, beating second-placed Gerhard Hennige from West Germany by almost a second. After Hemery crossed the line BBC commentator David Coleman famously exclaimed "Who cares who's third – it doesn't matter!" Hemery's British teammate John Sherwood turned out to be the bronze medal winner in a close finish that had to be settled by photo finish. Hemery's performance helped him win the 1968 BBC Sports Personality of the Year.