Earlier, Villanova Queen secured an emotional triumph for Irish trainer Jessica Harrington, who is recovering from breast cancer.
Colin Keane claimed his first victory at the meeting aboard the 25-1 chance in the Kensington Palace Fillies' Handicap.
Harrington was not at Ascot for the victory, but plans to attend later in the week.
"It means an awful lot to the whole team, it's been a very tough year. It'll be a good tonic for mum," said Harrington's daughter Kate.
On a day of big-priced winners, horses named after celebrities dominated in the Royal Hunt Cup as Jimi Hendrix beat Sonny Liston.
Rossa Ryan rode the 22-1 winner in a one-two for trainer Ralph Beckett and owners Chelsea Thoroughbreds.
Trainer Mick Appleby secured his first Royal Ascot winner with Big Evs in the Windsor Castle Stakes.
The 20-1 chance, named after racing fan Paul Evans who died last year, gave jockey Jason Hart victory after he was narrowly beaten on Highfield Princess a day earlier.
Dettori had to settle for third on Prosperous Voyage as 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 challenger Crimson Advocate just held on to win the Queen Mary Stakes by the narrowest of margins.
John Valesquez, riding for George Weaver, prevailed by a nose on the 9-1 shot from the fast-finishing Relief Rally.
Weaver was joined at Ascot by his wife and assistant trainer Cindy, who suffered a severe 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.
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