Bluestocking gave trainer Ralph Beckett and jockey Rossa Ryan their biggest win with victory in the Prix de l’Arc de Triomphe at Longchamp.
The four-year-old had been added to the field at a cost of £100,000 by owner-breeders Juddmonte after her impressive win in the Prix Vermeille at the Paris track last month.
The filly, who went off at 5-1, tracked the Aidan O’Brien-trained Los Angeles and Ryan Moore from the start.
She dug deep to finish strongly and hold off Aventure to land a record seventh win in Europe’s richest race for the late Khalid Abdullah’s racing operation.
“She is an extraordinary beast,” Beckett told ITV Racing.
“The draw helped. Rossa got her in the right place – everything went to plan and this is our best-ever day.”