Tac De Boistron, who failed to live up to his potential in Australia, has taken Group One honours in France for new trainer Marco Botti.

The six-year-old returned to Europe after a stint with Mick Kent in Victoria where he was unplaced in two starts in last year's Geelong and Melbourne Cups.

His failure was put down to the hard tracks and he appreciated the softer conditions in the French St Leger to win by five lengths from Going somewhere.

"I was pleased he showed a nice turn of foot on this ground as it's very testing," Botti said.

"He travelled well in the race and Martin (Harley) said he settled well after getting him cover.

"In the straight he went for a gap that closed in front of him. Then when he switched him out the response was good and he quickened away really well.

"I think he's finished for the year. There's nothing left for him and we'll probably put him away. I'll speak to the owners and hopefully they will keep him for next year.

"There are plenty of good races over two miles for him and he's a horse that has probably improved with age. He is very sound, straightforward and is holding his form."