Highfield Princess ran out a game winner of the Prix Maurice de Gheest at Deauville to land the first Group One of her career.
John Quinn's mare enjoyed a great campaign last season, with her first win coming off a mark of 83 before she scored at Royal Ascot in the Buckingham Palace Stakes.
She continued to progress and finished a respectable sixth at Ascot on Champions Day, but began this season attempting to get qualified for All-Weather Finals Day.
That has proved the springboard to her success as, having won at Newcastle against her own sex, she went on to land the 1895 Duke of York Stakes against the boys and was just over a length behind Naval Crown in the Platinum Jubilee last time out.
Always handy under Jason Hart, she had her Ascot conqueror for company but a furlong out she put her stamina to good use and began to stretch away.
Owen Burrows' Minzaal burst out of the pack to claim second with Charlie Hill's Garrus just behind in third, but Richard Fahey's Perfect Power was well beaten.
Hart told Sky Sports Racing: "The boss had this race mapped out after Ascot and he is never far wrong when he targets one.
"She's really special. She's owned by John Fairley who owns John's yard, he also bred her so it's very special."
It was also a first Group One win for Hart, who added: "Obviously these are the races everyone wants to ride in.
"I've had a couple of near-misses, in the Abbaye with El Astronaute and Safe Voyage in the Foret, but it's nice to come here and get a Group One.
"She's very versatile regards trip and I was a small bit worried about the ground, but she proved me wrong."