1924 was also the year in which he won his first English Classics - Diophon in the 2,000 Guineas and Salmon Trout in the St. Leger. However, both horses finished unplaced in the Epsom Derby won by Sansovino, and for the rest of his life this was the race on which the Aga Khan set his sights.
At that point in time the Aga Khan believed he should already have won a Derby with Papyrus. That is, if only George Lambton had put more faith in pedigree and less in conformation. He recorded in his memoirs: "I wired Lambton and I wrote posthaste to Dawson urging the purchase of this colt by Tracery ... Mr. Lambton did not like him, finding him too small and on the stocky side. That shows how little we ought to go by the make and shape of a yearling, so long as his legs are sound and he is neither a giant nor a lilliputian." By the time of his death in 1957, however, the late Aga Khan had garnered a record five wins, six seconds and three thirds in the Blue Riband of the turf. Given the strength of the competition in this race, year in and year out, such a record is truly astonishing. In The History of the Derby Stakes, Roger Mortimer notes that the Aga Khan "shares with Lord Egremont the distinction of having won the Derby five times". Lord Egremont ‘s victories started back in 1782 with Assassin in the third edition of the Derby and spread over a period of 44 years. Yet Mortimer notes one significant difference "the Aga’s winners were unquestionably three-years-olds while Lord Egremont’s in all probability were not!"
The first of the Derby runners-up was Zionist but he finished eight lengths behind Manna in 1925. There was, however, a Classic waiting in the wings when four weeks later Zionist blazed the trail in the Irish Derby. Other Epsom runners-up who followed the same route with similar success were Dastur in 1932 and Turkhan in 1940. The later achievements of Nathoo and Hindostan in 1948 and 1949 ensured that the Aga Khan’s haul of Derbys at the Curragh matched that at Epsom.