Frankie Dettori claimed a winner at his last Royal Ascot meeting as he took the Queen’s Vase aboard Gregory.
The 52-year-old Italian, who will retire at the end of the year, guided the John and Thady Gosden-trained pairs favorite home from Saint George.
“I couldn’t be happier. I thought the winner would never come his year,” said Dettori, who finished second three times on Tuesday.
Earlier, Mostahdaf surprised to win the Prince of Wales’s Stakes.
Gregory could give Dettori the chance of one last Classic later in the year, with the St Leger at Doncaster a potential target.
The jockey had a frustrating opening day which earned him a nine-day suspension for sloppy riding, which he will serve next month.
But he set a perfect pace from the front on the well-backed Gregory to secure his 78th Royal Ascot winner, which he celebrated with his signature flying dismount.
mostahdaf, a 10-1 chance from Jim Crowley for trainers John and Thady Gosden, who cruised the race before speeding away from a high-quality field in the Prince of Wales’s Stakes.
2-1 favorite Luxembourg was four lengths back in second, with 2021 Derby winner Adayar in third.
“It was a fantastic race. We’ve always held him in high regard,” said winning jockey Crowley.
My Prospero finished fourth, with the well-regarded Bay Bridge just fifth.
Ryan Moore had led from the start against 2-1 favorite Luxembourg but was no match for Mostahdaf, who was runner-up to Broome in the Hardwicke Stakes at Ascot last year.
The Shadwell-owned winner had finished last in the Prix de l’Arc de Triomphe in October but bounced back with victory in Saudi Arabia this year before finishing fourth to Japanese star Equinox in Dubai.
“The ground has dried out, which he’s really liked. He’s run a couple of times on soft ground and he’s worked on it,” said John Gosden.
“He won in Saudi Arabia in style and then took probably the best horse in the world, Equinox, and we refreshed him for that.”
Gosden said Mostahdaf would target the Juddmonte International in York in August.
Before, Reina Vilanova it was an emotional triumph for Irish coach Jessica Harrington, who is recovering from breast cancer.
Colin Keane took his first win at the meeting with the 25-1 chance in the Kensington Palace Fillies’ Handicap.
Harrington was not at Ascot for the win but plans to attend later in the week.
“It means a lot to the whole team, it’s been a really tough year. It’s going to be a good tonic for mum,” Harrington’s daughter Kate said.
Dettori, who rode at his last Royal Ascot before retiring this year, had to settle for third on Prosperous Voyage when Rogue Millennium won the Duke of Cambridge Stakes.
The 10-1 winner, ridden by Danny Tudhope for trainer Tom Clover and the Rogues Gallery syndicate, was a supplementary entry for the race and beat Random Harvest by a neck.
American rival Crimson Advocate just won the Queen Mary Stakes by the narrowest of margins.
John Valesquez, with George Weaver, won by a nose in the 9-1 shot of the fast-ending Relief Rally.
Weaver was joined at Ascot by his wife and assistant trainer Cindy, who suffered a serious brain injury in a riding accident last year.
King Charles III and Queen Camilla attended again on Wednesday, but their two runners, Reach For the Moon and Circle Of Fire, finished out of the places.
