It may not have gone as scripted but Westover and Rob Hornby found a way to win their first Group One together in the Grand Prix de Saint-Cloud.
Sent to France instead of taking in Saturday's Coral-Eclipse, Ralph Beckett had targetted this race to get the former Irish Derby star a second career victory at the top level.
The plan included sending stablemate Malabu Drive over as a pacemaker for the typically keen-going Westover.
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Although Dougie Costello was able to set a furious early pace, Malabu Drive could not last much further than the first bend, leaving Hornby to chase Junko and Tunnes, with main rival Zagrey in his slipstream.
To his credit, Westover kept things honest as he hit the front a long way from home and Hornby was all action to keep Zagrey at bay.
An emotional Hornby told Sky Sports Racing: "It's really dream come true stuff. These are colours I grew up watching and there is such prestige to them, so to be able to carry them to Group One success is a true honour.
"Ralph has trained this horse so well from two to three to four. I have to thank Barry [Mahon, Juddmonte's general manager] and everyone at the team.
"The pace was good early on. Dougie [Costello] was able to keep the pace honest early on but when he dropped away, I was able to keep Westover going and stoked up."
Beckett said: "Inevitably there was pressure as it was a long time since he won, over a year, and the longer that goes on the harder it gets.
"There was nothing wrong with his two runs this year, he's only had the one blip in the King George. He was great today and it was a very fast time.
"For so long we had a reputation for training long-distance fillies, so it's important to change the dial, as Angel Bleu has done as well.
"I think we'll either stay at a mile and a half or even have a conversation about going up in trip, because the peloton came to him, but he stretched away in the last half a furlong.
"We'll enjoy today and see what comes next, this was important.
"We'll certainly consider the King George and see how he is closer to the time. There will be a bit of a monkey on the shoulder saying 'is this a good idea?' after what happened last year, but we'll see.
"The Arc will be under consideration too, he ran a great race in it last year (sixth) but got stuck in the ground."