Ryan Moore completed the full set of British Classics as the tenacious Capri dug deep for him to land the William Hill St Leger at Doncaster.

Moore and the Aidan O’Brien-trained grey proved an unbeatable combination in a stirring finish to the £700,000 QIPCO British Champions Series contest – the pair repelling the persistent challenges of Crystal Ocean and Stradivarius.

The son of Galileo became the first horse since Triple Crown hero Nijinsky in 1970 to win the Irish Derby and the St Leger, in his first race since his success at the Curragh 11 weeks earlier.

John Gosden’s Stradivarius looked a real threat on the far rail, but Capri, the 3-1 favourite, was already close to the pace and set sail for home inside the final quarter-mile.

Crystal Ocean, trained by Sir Michael Stoute, made a strong run from the rear, but Capri would not be denied and scored by half a length, with Stradivarius just a short head away in third.

“When Crystal Ocean came to him, he dug in,” Moore said. “He’s done very little wrong in his career and has progressed from race to race. It was a really hard race, but he didn’t look like a horse who’d had a hard race. I just feel it was a very good Leger – in normal years the first three would be worthy winners.”

On winning the race for the first time, he swiftly replied: “It means you have to win it again, really.”

O’Brien, winning his fifth Leger, said: “We were all delighted with him. He had a little blip at York time (when he missed the Great Voltigeur). We were a little worried coming here, but Ryan gave him a class ride.

“We knew if we set a good pace for everyone we’d find out who the best horse was in the straight. He’s a horse with a lot of class, which we saw in the Irish Derby. When Ryan wanted it, he gave it to him.

“Seamus (Heffernan) rides him a lot at home and has always been a big believer in him. He always said he had class and that he would stay.”

As for future plans, he said “The lads (Coolmore) will decide what they want to do – run him again or put him away. He’s probably a mile-and-a-half horse with class, so he’d have no problem going a mile and a quarter.

“He has a great cruising speed and we always thought he had courage and stamina as well as class.”

Stoute said of Crystal Ocean: “I’d prefer to have won it, but he ran a great race, we’re thrilled with him. I thought he was going to win, but we won’t run him beyond a mile and a half again. It was always a danger that he was a mile-and-a-half horse and that’s his trip.

“Jim (Crowley) gave him a lovely ride and I always felt he might win. Jim reported he was always pretty confident, but he was just outstayed.”

Gosden has Champions Day at Ascot on October 21 in mind for his runners. “He (Stradivarius) has run a cracker. It was a relentless pace, very strong and there was no hiding place.

“If he comes out of it well he will go to Ascot for the stayers’ race (the Qipco British Champions Long Distance Cup). Coronet has run a lovely race (fifth) and she will go to Champions Day for the Fillies’ & Mares’ race.”