Marathon from the start at Windsor Castle to the royal entrance to the White City Stadium, followed by a lap (586 yards 2 feet; 536 m) of the track, finishing in front of the Royal Box. The course was later altered to use a different entrance to the stadium, followed by a partial lap of 385 yards to the same finish. The modern standard distance for the marathon was set by the International Amateur Athletic Federation (IAAF) in May 1921 directly from the length used at the 1908 Summer Olympics in London. An official IAAF marathon course is 42.195 km (42
Athletics at the 1908 Summer Olympics – Men's marathon yards on the track") eventually became the origin of the modern Marathon distance of "no less than 42.195 km". According to the book "The Marathon Makers" by John Bryant, the first mile of the 1908 Olympic Marathon course was remeasured by John Disley in the late 1990s and was found to be 174 yards (159 m) short. The official report lists the leaders at each mile from the fourth to the twenty-fourth: Thomas Jack (miles 4–5); Frederick Lord (miles 6–14); Charles Hefferon (miles 15–24). Dorando Pietri of Italy caught Hefferon and sped up between Old Oak Common Lane and Wormwood