Exhort got up in the shadow of the post to spring a 25-1 surprise in the Weatherbys TBA Pipalong Stakes at Pontefract.
The Richard Fahey-trained filly, wearing the familiar colours of Cheveley Park Stud, was helped by the strong gallop as she dropped two furlongs down in trip to a mile for this Listed contest.
Towards the back of the field with a quarter of a mile to go, Exhort still had plenty to do at the furlong pole but responded to Paul Hanagan's urgings to land the spoils.
Exhort finished to such effect that she won by three-quarters of a length from last year's 1000 Guineas heroine Billesdon Brook.
The always prominent Agincourt was half-a-length away in third, with New Day Dawn fourth and last year's winner Clon Coulis only fifth.
Fahey said: "I'm delighted. She's a home bred filly of Cheveleys.
"We always felt she was a black-type filly. It's just taken her time to get there. She's just been a slow-burner."
Fahey confirmed the good early pace worked to her advantage.
"They went a good gallop, and it suited her - everything went right," he said.
"It was great to see her win, because it's the Cheveley Park stallion parade tonight - a good, timely win.
"The main aim was to get some black type with her. She'd been placed a couple of times, and this was just the added bonus."