William was riding Carol Toliver’s eight-year-old Billy Balou, who last year took the EquestrianClearance.com Senior Newcomers Championship, making him the first horse to win both titles.
“It’s important to realise how much of a team effort it has been to win this,” said William, who bred Billy Balou under his and Donal Barnwell’s Billy Stud banner.
“Right from breeding the horses through to producing and competing them, there are a lot of people involved and all of them play their part.”
William was the youngest rider to win a Foxhunter title at the age of 17 in 1984 with Once More, and in 2001 he won it again with Mondriaan.
Yesterday, William also took the Xerox Special Event Services Cup with Billy Angelo.
“It’s a great position to be in having good international horses as well as nice ones coming up,” he said.
Scott Brash claimed his first international victory since winning team gold in Greenwich, taking the Sky Sports Trophy on Liz MacTaggart’s Bon Ami.
“It’s a privilege to jump in front of this home crowd,” said Scott.
“It’s a fantastic show for us British riders, the atmosphere here is incredible and the spectators always give you such a warm welcome. It’s great to be able to repay their support.”
HOYS runs until Sunday 7 October.
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Don’t miss our full report on all the action from Horse of the Year Show in next Thursday’s magazine, on sale 11 October, 2012