Madison Du Berlais, winner of the 2008 Hennessy Gold Cup, has died of colic at the age of 12.
A 25-1 scorer of the Newbury showpiece, he went on to prove that was no fluke by beating Denman at Kempton later that season. He also lifted the totesport Bowl at Aintree in April of that year.
David Pipe's gelding was retired after his final run in December 2011 and had been competing in dressage events.
The Pond House handler told his website, www.davidpipe.com: "Madison was a great favourite in the yard and we enjoyed many happy times with him since buying him from a French claimer.
"His 2008-9 season in particular was stellar, with memorable victories not only in Newbury's showpiece but also at Kempton (where he demolished Denman) and Aintree in the totesport Bowl.
"He was retired from racing after his final run in December 2011 and had been enjoying himself competing in dressage events."