The Irish jockey was convincing at the finishing post on Ambivalent, despite a final sprint from Joseph O’Brien on Was and Kieren Fallon on Shirocco Star.
“They all had a go and she dug deep,” Murtagh said. “It’s been a great few weeks. It seems to happen like that; if you get on a roll it can keep going.”
Victory was Murtagh's second in this Group 1, 20 years after his first victory on Takarouna.
The win also belonged to the trainer Roger Varian, who is based at Newmarket.
“I told Johnny to be positive, send her forward, and told him he had nothing to lose,” Varian said. "And he gave her a brilliant ride because she’s got a quirk and is not easy."