Dartmouth just came out on top in a thrilling finish to the Betway Yorkshire Cup at York.
Making his challenge on the stands side rail, the royal runner got the verdict from Simple Verse, who was on the opposite side of the track.
Five horses were in with a chance in the final furlong and were spread all across the Knavesmire, but it was the Michael Stoute-trained Dartmouth (11-4 favourite) who got to the front close home to snatch the verdict by a neck from Ralph Beckett's 2015 St Leger winner.
The pace-setting High Jinx, having his first race for 747 days, kept on in gritty fashion and was just a neck away to claim third spot on his first start for Yorkshire trainer Tim Easterby.
Winning rider Ryan Moore said: "He felt very easy the whole way, he's got mile-and-a-half pace, he was just doing a little too much in stages.
"He travelled beautifully and is such an honest horse, but it didn't help that I was apart from them and he's done very well.
"That's his fourth Group race now, we know what he is, he's a very honest horse."
Queen Elizabeth II’s racing advisor John Warren pointed towards the defence of his Hardwicke Stakes crown at Royal Ascot over a mile and a half as being next for Dartmouth.
He said: "I didn't think he was going to get there because they were so wide. Ryan had this plan to come this side, so he knew what he was doing, but I don't think he anticipated they were going to be so far away width wise as they were.
"It was hard to see from the stands whether he was going to get up. It was a remarkable ride, he's an absolute professional.
"This horse is exceptionally brave, so tough and genuine. He always tries. Today proved he can pull out all the stops when he wants to.
"I suspect Sir Michael will be looking at the Hardwicke again. That's his sort of race.
"He's an interesting horse because this (an extended mile and five furlongs) is as far as he's gone. It will be interesting to see how the remainder of the season unfolds after Ascot. We will have to look at the opportunities.
"Hopefully he goes to Ascot with a real big shout."
He added: "The Gold Cup would be a big ask. The thing is he would give his all and may leave his whole season behind.
"My view is that he's so good at what he's doing there's no need to find out.
"I'd say it will be the Hardwicke and then we might try and find out if he is a Cup horse.
"Dubai was the plan after Canada, where it went wrong, but he had a setback which meant he couldn't go which was a shame as it would have been nice to have a runner at the Carnival.
"We've always regarded him as nearly a Group One horse but abroad, sometimes that is enough to win a Group One."