Hootenanny gave American trainer Wesley Ward his fourth Royal Ascot winner with a dominant display in the Windsor Castle Stakes.
Ward enjoyed a groundbreaking double with Strike The Tiger in the Windsor Castle and Jealous Again in the Queen Mary Stakes in 2009 and added to his tally with last year's Norfolk Stakes scorer No Nay Never.
Hootenanny, owned by the Coolmore triumvirate of John Magnier, Michael Tabor and Derrick Smith, was the trainer's first runner of a strong juvenile hand this year and was a strongly-backed 7-2 favourite in the hands of Victor Espinoza.
The juvenile got off to a fast start towards the stands rail and while his rivals tried throw down challenges right across the track, Hootenanny was in a different league as he came home with three and a half lengths in hand over 100-1 shot Union Rose.
It was a first Royal winner for Espinoza, who has enjoyed a memorable year having guided California Chrome to win both the Kentucky Derby and the Preakness Stakes.
He was hot favourite to complete the American Triple Crown in the Belmont Stakes earlier this month, but could only finish fourth.
Espinoza said: "He's pretty quick out of the gate and I tried to slow him down a little bit to save him for the end, I didn't want to burn him out.
"I was happy in the middle, I just wanted to go in straight lines.
"I've had a fantastic year, a Kentucky Derby and now a Royal Ascot winner."
Ward said: "He's a beautiful colt, he hopefully has a big future so we'll see what happens.
"One thing we found out in his last race was that he doesn't like the dirt, I sort of knew that going into the race and it went against my better judgement but we'll keep him to turf now.
"Paul Shanahan at Coolmore was a believer in me when I was nothing and he's stuck by me. I'd also like to thank Arlington Park, they let me breeze my colts on the turf which doesn't happen over there.
"He's scheduled to go back on Monday. I'm bringing Undrafted over for the July Cup, so we'll make a decision on whether he's coming back or not.
"We've got some more nice horses running for the rest of the week."