The Queen celebrated a victory at Royal Ascot in Diamond Jubilee year as her horse Estimate won the Queen's Vase.
Jockey Ryan Moore guided the 3-1 favourite to a five-length success which gave the monarch her first triumph at the meeting since 2008.
The three-year-old filly, trained by Sir Michael Stoute, provided her 21st win at the royal meeting but only her second since 1999.
Her Majesty was presented with the trophy by the Duke of Edinburgh.
He was always scheduled to present the Queen's Vase to the winning owner and it is thought to be the first time he has handed a trophy to his wife at her meeting.
Carlton House, also owned by the Queen, was runner-up to So You Think in the Prince of Wales's Stakes on Wednesday.
Her last success at Royal Ascot came with Free Agent in the Chesham Stakes four years ago, and her most recent winner before that was 1999 Edinburgh Stakes victor Blueprint.
Estimate returned to cheers in the winner's enclosure from an appreciative crowd after landing the two-mile contest from the Irish-trained horse Athens.
Stoute, who is based in Newmarket, said: "We tried to do it with Carlton House and we got beaten fair and square.
"But it's very nice to come to this meeting with runners for this owner with some sort of chance, particularly in Jubilee year.
"The Queen deserves the success. She contributes so much to racing and I'm sure the whole country will have appreciated the victory. And for me it's a great honour."
The trophy is one of only three at Royal Ascot - along with the Gold Cup and Royal Hunt Cup - that the winning owner gets to keep. Its design is changed each year, and approved by the Queen.
Ascot chief executive Charles Barnett said: "The reception Her Majesty received was amazing - I've never seen anything like it.
"There was a great flow of excitement, and while the Queen looked so calm, I think inwardly she was feeling very excited too.
"For me and for many other people that has been the highlight of the week."
Estimate had only run twice before, with one win - at Salisbury seven weeks earlier - but public support saw her go off as market leader at Ascot.
"On her form, I'd have thought she should have been about sixth favourite," said Stoute.
The Queen owns 41 horses in training, both on the Flat and over the jumps.
It was her second victory of the week after Set To Music won the Warwickshire Oaks at Warwick on Monday night.
Estimate was installed as a 16-1 chance for the St Leger at Doncaster in September by sponsors Ladbrokes, for which Epsom Derby winner Camelot is the 1-3 favourite.
The Classic, over a mile and three quarters, provided the last Group One winner in Britain for the Queen when Dunfermline triumphed in 1977, Silver Jubilee year.
But Stoute indicated the filly may not be aimed at the race, saying: "We'll see how she progresses but at this stage, I shouldn't think so."
Aidan O'Brien, trainer of Athens, said he was happy to take the runner-up spot behind Estimate.
"For once, I'm delighted to be second. I'm delighted for the Queen," he said.
And Rae Guest, trainer of third-placed Ed De Gas, added: "If you are going to get beat, it's nice to be beaten by the Queen."