Thomas Chippendale, yesterday's Hardwicke Stakes-winning horse, died of a suspected heart attack shortly after his victory.
Lady Cecil's winner on the final day of Royal Ascot, ridden by Johnny Murtagh, won the Group Two race in thrilling fashion before collapsing shortly past the post.
The four-year-old colt collapsed moments after crossing the line and, following treatment on the racecourse, was pronounced dead.
An emotional Lady Cecil, who has temporarily taken over the Warren Place yard's training licence following the recent death of her husband Sir Henry Cecil, said: "It was devastating, but at least it was quick and he wouldn't have felt anything.
"We didn't realise the horse had collapsed, so we came from the grandstand into the winner's enclosure feeling so happy and couldn't understand why it was rather quiet.
"Leading up to the race he was in such good form and really enjoying himself. When Luis [Villarroel, his groom] took him out for a pick of grass he was always the last one who wanted to come back in.
"We couldn't have been happier with him beforehand and he could not have won like that if he had not been a happy, sound horse.
"It's so awful to go from one emotion to another, from a hight to a low. It puts such a dampener on the day. But we have to carry on."
"It's just devastating the way it's finished," added Murtagh. "It should have been a great win. He lost his balance and I don't know what happened to him."
Owned by Sir Robert Ogden, Thomas Chippendale was running in his 10th career race and he had three previous wins, including last year's King Edward VII Stakes at the Royal meeting.
Officials at Ascot Racecourse offered their sincere condolences to the connections of Thomas Chippendale after the incident.
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