Westover turned the Dubai Duty Free Irish Derby into a procession with a dominant display at the Curragh.
Thought by many to be an unlucky third at Epsom behind Desert Crown, Rob Hornby had been replaced by Ireland’s champion jockey Colin Keane for his Classic assignment.
Keane was intent on not letting the early pace-setter French Claim gain too much of an advantage in front and while Westover was tracking the pace, his main market rival, Aidan O’Brien’s Oaks winner Tuesday, was dropped out by Ryan Moore.
Lionel was one of the first beaten and when Moore tried to make up ground on Tuesday, Keane asked Westover to go and win the race two furlongs out.
The Ralph Beckett-trained colt galloped clear in relentless fashion and while Piz Badile gave game chase, he was no match for the impressive winner.
A winning distance of seven lengths advertised his superiority with a further two back to French Claim in third. Tuesday came home in fourth.
The winner was cut to 4-1 from 10s by Paddy Power for the King George VI And Queen Elizabeth Stakes, while he is 7-4 from 4-1 for the St Leger with Ladbrokes.
Keane said: “I suppose every jockey says the race they would like to win is the Epsom Derby, the second one would be the Irish Derby I think. It is great to win our home Derby. It’s unbelievable.
“Full dues to Rob Hornby, I rang him this morning and he told me everything I needed to know about the horse – a true gentleman. He said the horse gets the trip well and he’ll get further, so don’t be afraid to use him up. He said one thing he will do is get to the line. Ralph said the same and, when you turn in, get him rolling and you’ll stay going.
“I was (a bit keen for a furlong) but once he got in behind one, he gave me a beautiful ride. He’s a monster of a horse, so he is only going to be a better horse next year.
“I’m very grateful and thankful to the owners, the Juddmonte family, they have been very good and loyal to us since they joined Glenburnie (retained trainer Ger Lyons’ stable). I’m very thankful that they put their faith in me to ride this horse today.”