Sam Darling Snr. (1852-1921) was a thoroughbred horse trainer, running the Beckhampton yard in Wiltshire for thirty three years. In addition to the winners of seven English Classic Races, Darling trained the great Willonyx, winner of the Ascot Gold Cup in 1911 and the Cesarewitch Handicap. When he retired in 1913 his son Fred Darling succeeded him at Beckhampton and went on to become England's greatest trainer of the 20th century. His other son Sam Darling Jnr. was already training at Newmarket.
Clarence Hungerford Mackay (1874-1938) was an American multi- millionaire and racing enthusiast, having inherited much of an estimated $500 million fortune upon his father's death in 1902. Mackay sent a bay colt, Won-by-Waiting, to Englandin 1907 to prepare for the English Derby, the St. Leger and other rich stakes in 1909. Upon his arrival the colt was sent to be trained by Sam Darling, who was by this time well reknowned for his previous successes.