Eight years later Cos achieved a still more remarkable success. It was a cool October afternoon when Rustom Pasha, the second produce of Cos, and already winner of the Eclipse Stakes at Sandown, lined up at Newmarket for the last great weight-for-age race of the season, the Champion Stakes. His opposition included such fine Classic winning contemporaries as Diolite (2,000 guineas), Fair Isle (1,000 guineas), and Singapore (St. Leger). Grace Dalrymple, whose Classic engagements had been voided by the death of her owner Lord Dewar, was a sentimental favourite and tried to make all the running but, having beaten off Fair Isle, was finally overtaken by the patiently ridden Rustom Pasha (Harry Wragg) who won by three quarters of a length. No one looking on could have appreciated just how significant a moment in turf history they had witnessed.

Ruston Pasha had become the first of no less the ten home-bred winners of this contest for the Aga Khan and his family. This incredible tally was recently bolstered by Kalanisi's win in a memorable renewal in 2000. In winning that year's Champion Stakes Kalanisi defeated seven individual Group One winners including Arc winner Montjeu and classic heroine Love Divine.

Other notable winners for the Aga Khan family include such super-stars as Nasrullah, the greatest of all the Aga Khan-bred stallions; Migoli, the only English-trained winner of the Prix de l'Arc de Triomphe in the period spanned by the years 1924 - 1970; and Petite Etoile who at 134 is still the highest Timeform rated family racemare. In this decade, besides Kalanisi's win the present Aga Khan has also owned and bred the winners of the French and Irish equivalents, the Prix Ganay at Longchamp with Kartajana (1991), Valanour (1996) and Astarabad (1997) and the Irish Champion Stakes at Leopardstown with Timarida (1996) and Daylami (1999).