Jim Bolger's charge had won the Qipco 2000 Guineas at Newmarket earlier in the season, as well as the French equivalent on soft ground, and the Irish version.
As he had already won a Guineas trial before Newmarket he was having his fifth run of the season - and had obviously thrived on it.
Kevin Manning had the son of Dawn Approach in the box seat throughout, and in truth, the result never looked in any doubt.
The veteran rider waited until a furlong and a half out before pushing the button; the response was immediate.
The 7/2 favourite shot clear and crossed the line four and a quarter length clear of Lucky Vega. Battleground ran on for third, with Maximal fourth.
Bolger told Sky Sports Racing: "I'm very relaxed about it. I have tremendous confidence in this horse, and I was expecting him to go and do that. Thanks to all my staff and everybody who has helped.
"We always knew he was hardy from the word go, even when he was being broken in you couldn't keep him quiet.
"We've bred from the family since the very early 1980s, so a long time.
"When you have a horse winning the St James's Palace like that you don't really think about all the relatives and the breeding, you wouldn't care if he came to you off the back of a truck as long as you had him.
"This horse is so hardy he's unbelievable, you have to give it to him to keep his back down."