Roger Varian's stable is mourning the loss of star performer Defoe, who suffered a fatal injury on the gallops this morning.
The nine-time winner raced to his biggest success last summer, when taking the Group One Coronation Cup at Epsom.
On his next start, the popular grey won the Hardwicke Stakes at Royal Ascot, a race he finished third in this year on what was his final start.
"It is probably not a safe assumption that only those who were closely connected with the horse will be heartbroken that he has left this life," Varian said.
"Although not large in stature Defoe had the heart of a lion and his adoring fans from around the world will no doubt join us in mourning his loss and celebrating his achievements."
In 22 races, the six-year-old won more than £800,000 in prize money on the racecourse.
He finished second in Group company three times on his travels, at Baden-Baden, Meydan and Munich.
Newmarket-based Varian also recently lost 2020 Royal Ascot winner, Mountain Angel, while he was being prepared for the Sky Bet York Stakes.
"It is a great sadness that Defoe’s final race came at an eerily empty Royal Ascot where he ran an admirable race to finish third in the Group Two Hardwicke Stakes, a scene that was a world away from those jubilant celebrations with Sheikh Mohammed Obaid in the winner’s enclosure twelve months previously," Varian added.
"We can’t help but have favourites and Defoe was everyone’s favourite horse; from his groom Mark, head girl Dee, regular rider Korrie and to Roger and Hanako’s children he was a star and such was his popularity with them that they had a rocking horse made in his image.
"A lasting memory for a great horse."
