Desert Hero gave the King and Queen a historic success at Royal Ascot in the royal silks, winning the June 22 King George V Stakes at odds of 18-1.
The 3-year-old colt pounced late under Tom Marquand to win on the line from Valiant King and provide King Charles III with a first success at the royal meeting since the death of Queen Elizabeth II last September.
The winner was trained by William Haggas, who was in the royal procession before racing on Wednesday. It was just the King's fourth runner at Royal Ascot this week and more than twice the odds of his first three. The late Queen bred the chestnut son of Sea The Stars.
The King collected the prize with Queen Camilla, who could be seen close to tears in TV pictures of the royal box in the aftermath of the surprise win. Zara Tindall, granddaughter of the late Queen Elizabeth II, said the victory was bittersweet for the royal family.
She said to ITV: "Think how proud our grandmother, the Queen, would've been. To have a winner for Charles and Camilla and keep that dream alive was incredible. It's a new excitement. Like all those owners that come here and have a horse here having that dream, that hope, and then fulfilling it is incredible.
"The horses are the main game here, that's why we get involved and love them and the competition, the adrenaline—it's indescribable."
Marquand said it was one of the biggest victories of his career. It was his fourth at Royal Ascot and first at this year's meeting.
He said: "Genuinely, that's one of the proudest moments I've had in the saddle so far. It's not to the same level that Estimate was on but I grew up watching horses like that win for the Queen and to ride the King's first Royal Ascot winner is unbelievable. It's a dream.
"Racing has an amazing way of making things happen when they're meant to. Wednesday was a tough day, in racing terms, but Royal Ascot is the pinnacle. Riding a royal winner at the royal meeting is so, so special.
"I had to thread the eye of the needle but he was supremely game. As the Haggas team shows time and time again, they just get it right time and time again."