Racing will be the winner, according to Willie Carson, if Desert Hero is able to replicate his historic achievement aboard Dunfermline and carry the royal silks to Classic glory in Saturday’s Betfred St Leger.

It was 1977 when Carson famously got the better of Lester Piggott and Alleged to give the late Queen Classic success in the Doncaster showpiece, during the same season the duo also tasted Oaks glory at Epsom in the height of the Silver Jubilee celebrations.

Dunfermline remains the last royal Classic winner, but now 46 years later the attention is once again on Town Moor as the William Haggas-trained Desert Hero attempts to add his name to the history books.

Having already provided the King and Queen with their first Royal Ascot triumph, the son of Sea The Stars, who will be ridden by Tom Marquand, now bids to add one of the sport’s crown jewels to his ever-growing CV.

“If the King wins then that will help racing, without a doubt,” Carson told the PA news agency.

“I rode two Classic winners for the Queen, but she wasn’t there either time. She was too busy with the Silver Jubilee celebrations for the Oaks and she was at Balmoral for the Leger, but I spoke to her on the telephone after.

“It’s a very good race, our oldest Classic, and it has the makings of a good horse race and the makings of a good story and we’re looking forward to a marvellous race.

“And if the King does arrive at Doncaster on the day and wins, then there is only one winner – racing.”

Carson won the St Leger three times, but 35 years after his final Doncaster triumph aboard Minster Son, another member of the family now has his chance to add his name to the annals of Britain’s oldest Classic.

That is because Desert Hero has been helped in his preparation for the big race by Carson’s grandson Luke, who rides the King George V Stakes and Gordon Stakes scorer in his work and is a key figure in the colt’s journey to the top.

“He’s looked after and ridden every day by my grandson, his name is Luke Carson,” continued the 80-year-old, who partnered 17 British Classic winners during his decorated career.

“He rides him in the morning, looks after him, he’s his baby.

“So I will be very happy if the King wins, for all sorts of reasons. He’s obviously got a chance, but I wouldn’t say he has as good a chance as Dunfermline did.

“Not only was that Leger famous because the Queen won it, but it was the only time in his career Alleged was beat. It was an incredible race and she was a very good filly, Dunfermline.”

Not only does Carson have the family connection with Desert Hero to look forward to, he also owns a half-sister of the dam of ante-post favourite Gregory, and it promises to be a huge afternoon for the Scotsman, who may struggle to juggle his loyalties in the closing stages.

He added: “It’s a race I won three times. The race was quite kind to me.

“The horse Gregory, I own the dam’s half-sister called Leah. For me it is a big day all round.

“We’ve got a few irons in the fire and I guess I’ll be shouting for them both. Maybe a dead-heat!

Gregory heads to Doncaster Moor as market leader despite losing for the first time in the Great Voltigeur at York.

It was Aidan O’Brien’s Continuous who lowered the Golden Horn colt’s colours on that occasion, but Carson believes Gregory could be seen to better effect this weekend.

He said: “I saw an interview that John Gosden gave and I agreed with everything he said about why Gregory got beat at York.

“Unfortunately Frankie (Dettori) rode a fantastic race in the following race that day (Mostahdaf in the Juddmonte International Stakes), but he fell into a bad trap on Gregory by going too fast.

“John Gosden pointed that out and he also pointed out that when the race was over and he was beat, and Frankie had decided that was it, the horse still ran on.

“So Continuous is not certain to beat him at Doncaster. I think Frankie thought he would be able to dictate at York, but I’m afraid the dictation got thrown out the window because he had two people annoying him all the way round.”

He has also narrowed the stamina-sapping one-mile-six-furlong contest down to the three at the head of the betting and is relishing the prospect of three of the weighing room’s best slugging it out to lift the trophy.

“It looks like those are the three (Gregory, Continuous and Desert Hero) that should be winning the St Leger and I would say it will be the horse that gets the best ride, basically  – the one who it clicks for and whoever gets it right,” said Carson.

“O’Brien will organise the pace and it will be up to Frankie, who is normally very astute when it comes to tactics, I imagine he will not get it wrong this time. Of course, Ryan Moore will just sit on the tail of Frankie, that’s how I see it, whether it happens is another matter.

“You’ve got three of the top jockeys at the top of the game and we’re in for a treat.”