Cantelo was made favourite ahead of Petite Etoile, whose pedigree had led to doubts regarding her stamina over one and a half miles.
[5] Two weeks after her Oaks defeat, Cantelo was sent to Royal Ascot for the Ribblesdale Stakes which she won comfortably from the Prix des Lilas winner La Coquenne.
A month later, Cantelo returned to Ascot for Britain's most valuable and prestigious all-aged race, the King George VI and Queen Elizabeth Stakes.
[7] In the St Leger, Cantelo started at odds of 100/7 in field of eleven, with The Derby winner Parthia being made the odds-on favourite.
Hide sent Cantelo into the lead in the straight and she won by one and a half lengths from the Irish Derby winner Fidalgo, with Pindari taking third ahead of Parthia.
She was the first Yorkshire-trained winner of the race since Apology in 1874, but was given a hostile reception by some racegoers who felt aggrieved by the abrupt improvement in the filly's form since the Park Hill Stakes.
She was not a great success as a broodmare but did produce one good horse in Cambridge (sired by Saint Crespin) who won the Blue Riband Trial Stakes at Epsom in 1965 and later stood as a stallion in Florida.