Sir Percy dam Percy's Lass won the Group 3 September Stakes in 1988 (and subsequently died of colic when Sir Percy was a foal. Sir Percy was the last of her offspring) and his damsire Blakeney won the Epsom Derby himself in 1969. Sir Percy was named after Sir Percy Blakeney, the hero of the novel "The Scarlet Pimpernel". In November 2003 Sir Percy was sent as a weanling to the Tattersalls sales. He was bought for 20,000 guineas by Will Edmeades bloodstock, acting on behalf of Anthony Pakenham. Pakenham bought the colt as compensation for losing a National Hunt Horse. Sir
Sir Percy Sir Percy remained in training for 2007 but failed to win in three starts. His first race of the season came in the Dubai Sheema Classic at Nad Al Sheba Racecourse on 31 March. He was struck into just after the field left the stalls but ran on to finish fourth to Vengeance of Rain. For his next race on 1 June he returned to Epsom to contest the Coronation Cup, finishing sixth of the seven runners behind Scorpion. On his final racecourse appearance Sir Percy was last of the six runners behind Manduro in the 2007 Prince of Wales's