The gelding was put down yesterday (Tuesday, 28 July), due to old age.
“Very sadly Tamarillo was put to sleep — at 23, age had simply caught up him,” read a statement on William’s website.
With William Tamarillo won countless events, including Badminton in 2004 and Burghley in 2008.
By Tarnik and out of Mellita, Tamarillo was bred by the Guinness family in 1992 at the Biddesden Stud.
He formed a wonderful partnership with William throughout his career and was a popular sight at British Eventing (BE) fixtures and a staple on British championship teams.
He started his eventing career under Diana Burgess in 1997, when he was placed fifth in a pre-novice section at Tweseldown. Diana evented him up to intermediate level, before William took over the ride in 1999, after a lucky suggestion by Mark Todd.
William always spoke highly of the horse, but admitted that he was no easy ride.
“He can be everything all at once — spooky, lazy, sharp, exuberant, sensitive. He’s extraordinary and unique,” he told H&H while the horse was competing.
The pair won the two-star at Blarney in 2000, before finished second at Blenheim later that season.
In 2002 he was second at Badminton, securing him a place on the bronze medal-winning British team for the World Equestrian Games (WEG).
In 2004 he won Badminton, and competed at the Athens Olympics, where they won team silver although Tamarillo had to be withdrawn from a promising individual place after an injury on the cross-country. The next season the pair competed at the Europeans, where they won individual silver and team gold.
He represented Britain for the final time at WEG in Aachen in 2006, and was part of the team that won silver.
Tamarillo rounded off his stellar career in 2008 with an emotional win at Burghley.
He was retired from eventing at the end of 2009 after a reoccurrence of an old leg injury.
“Tamarillo earned 1,636 BE points, and was one of the world’s most successful eventing horses, and his huge personality came through in his performances earning him fans worldwide,” continued the statement.
“He has spent a long and happy retirement under the watchful eye of Jackie Potts [William’s longstanding head girl] — who travelled with him to every major championship and did the most wonderful job in keeping him in peak condition for so many years, he was in great shape right until the end.
“We are so sad for MW, Finn, Rebecca and Rory Guinness, who have owned and cherished him throughout his life. All of us at Fox-Pitt Eventing will miss him hugely.”
However, his genes will live on as his clone remains. In 2013 H&H broke the news that Tomatillo, a colt, was born in San Antonio, New Mexico.
The colt looks like Tamarillo’s 100% match, with William describing it as “uncanny” when the foal was born.
Despite his resemblance to Tamarillo, it is still unclear whether Tomatillo will compete.
“We will breed from him as soon as possible to see what kind of animals he produces,” MW Guinness said last year.
“We wouldn’t dismiss the idea of having him in competition, but breeding is the number one objective of this exercise.”