Tac De Boistron became only the third dual winner of the Prix Royal-Oak when leading home a British-trained one-two in the Longchamp staying event.

Sent off the 7-4 favourite on his preferred testing ground, Marco Botti's grey was brought through with a powerful effort from his place in the middle of the field by Martin Harley and won by a length.

James Fanshawe's High Jinx made most of the running through the extended mile and seven furlongs and battled back under James Doyle to pinch the runner-up spot from Narrow Hill by a nose.

Dermot Weld's Pale Mimosa held every chance under William Buick but could finish only fourth.

The race recognised as the French St Leger has been a Group One open to older horses since 1979 and Amilynx and Westerner were the only previous performers to have won it twice.

The result was all the more meritorious as Tac De Boistron was returning from a long lay-off, having raced just twice during the spring since his previous Royal-Oak triumph.

Botti said: "I'm really chuffed. He had a setback earlier in the year and it took a bit longer than we thought. He had been cantering away but he hadn't had much of a preparation for a Group One, so it's credit to the horse.

"The ground was right, and he has got away with it even if he might have been short on fitness.

"There is nothing left for him on his ground but hopefully he will have a clear preparation now through to next year. He's seven, but looking at that he still seems to be getting better and hopefully he'll be around for another couple of seasons."

Paddy Power offer Tac De Boistron at 20-1 for next year's Gold Cup at Ascot.