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
Black Knight (Sir Percy) foe of the evil knight Mordred the Evil (Arthur's traitorous "nephew") and Morgan le Fay, in time Sir Percy retired his dual identity and married Lady Rosamund. Percy is eventually killed at Castle Scandia by Mordred during the fall of Camelot when stabbed from behind with an enchanted blade made of the same material as his own Ebony Blade - although Mordred then dies himself of wounds inflicted by Arthur during the Battle of Camlann earlier that day. Merlin ensures that Percy's spirit will live on by casting a spell that will revive his ghost if Mordred should ever return.