Westover bounced back from finding trouble in-running when third in the Cazoo Derby at Epsom to land the Dubai Duty Free Irish Derby in great style.
Sent off the 11/8 favourite with Oaks winner Tuesday, Westover powered away on the front end to win by seven lengths under Colin Keane with Aidan O'Brien's filly never getting into contention.
Piz Badile put his Epsom defeat behind him with a better run in second, but this was all about the dominant Ralph Beckett-trained winner.
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, 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.”
WATCH: Westover storms to Irish Derby success under Colin Keane
Beckett reaction: 'King George an option'
Beckett said: “Colin was positive on him from the outset and took the bull by the horns. Rob Hornby spoke to him at lunchtime today and encouraged him to ride him that way.
“It’s important that you go out with your boots on in these occasions and Colin certainly did that today. I really didn’t think he would win like that at this stage. He’s a big horse and still a work in progress. He’s going to get better with age.
“I never felt he was going to stop when he got into his stride. He drifted out a bit into the middle of the track and is still, as I say, a work in progress. I hope there is more to come with him. He has a great temperament and that shone through today.
“This was always a race that would fit in well. The track suits him and it’s wonderful to get it done. It’s a big day for us.
“He’s going to develop from three to four, never mind through the rest of the year you would think.
“We’ll discuss it with the family and everybody to see what we do next. It depends how he comes out of today. He’s in the King George and that would certainly be an option.
“He’s not ground dependent and that is important. We can really go where we want, when we want, when we are happy with the horse.”
O'Brien reaction: 'There will be better days for Tuesday'
O’Brien was full of praise for the placed runners, but felt Tuesday is capable of better in the future.
He said: “I wouldn’t take anything away from the first three horses, but anything that sat handy stayed handy. It was probably hard with the wind to get into it.
“The winner is a very good horse, no doubt.
“There is probably more to come (from Tuesday) and hopefully she will run better the next day.”