Having sent out the mighty Yeats to win the race on four occasions between 2006 and 2009, there is every possibility the lightly raced four-year-old could dominate the staying division after claiming what at one stage looked an unlikely victory.
Appearing just 13 days after winning the Saval Beg on his reappearance, the son of Galileo was backed into 10-11 favourite to give the master of Ballydoyle his seventh winner in the two-and-a-half mile event.
All looked to be going well for last year’s impressive Irish St Leger winner with Ryan Moore giving his mount ample cover in the middle of the field through the early stages, as French raider Mille Et Mille blazed a trail up front.
It was not until the final half-mile when the drama began where, after sitting in a seemingly useful position, Order Of St George found himself shuffled back with more horses in front of him than behind him and left with what looked a mountain to climb.
After being forced to sit and suffer, the split eventually came for Moore and when it did the response was immediate, with the pair moving through the gears to pass the long-time leader, who had kicked off the home turn, at the furlong pole.
Once in command, Order Of St George was not for stopping and having endured a rough ride to cause a moment of panic for punters, he eventually crossed the line three lengths clear of Mizzou, with Sheikhzayedroad a further two-and-a-quarter lengths back in third.
Clever Cookie finished seventh for Leyburn jockey PJ McDonald and Malton trainer Peter Niven.
O’Brien said: “You never know if they are going to get the trip if they have never been over that.
“He won the Irish St Leger on soft ground by 11 or 12 lengths off a strong pace and if he wasn’t going to stay there were very few horses that would.
“It was great. He is a brave horse and Ryan Moore gave him a great ride.
“The lads did a great job getting him back as he had a little setback at the end of last year and we were a little bit worried if we were going to get there.
“Donnacha (O’Brien) was very happy after riding him at Leopardstown and I thought he had a chance then.
“He is a seriously class horse. Ryan switched him out and he came down the middle of the track and just kept galloping. He just has a big Rolls-Royce engine.”
The defence of his Irish Leger title is high on the priority list before a potential assault on the Prix de l’Arc de Triomphe, for which he was introduced at 16-1 by Leeds-based William Hill.
O’Brien, who had recorded his 50th Royal Ascot winner when Even Song won the preceding Ribblesdale Stakes, added: “I think the plan is to give him a little rest and bring him back and get him prepared for the Irish St Leger and if that all ends well, he could go for the Arc.”
Moore was impressed by the manner of the victory given the trouble he encountered in running.
He said: “It was stop-start. It was a nightmare really. It was not by choice that I had nowhere to go. I wanted to give him a bit of cover as he had never been beyond two miles before, but it got messy.
“He’s a class horse and class horses win races. He picked up very well and after two-and-a-half miles, he was pouring it on at the end.”
Earlier, the resurgence of Sheikh Mohammed’s Godolphin operation continued with Hawkbill winning the Tercentenary Stakes under William Buick.
The horse’s fifth consecutive success, winning trainer Charlie Appleby said: “We always knew he was a nice horse, and it was a great ride by William. I said the best way to ride him was to ride him like the best horse in the race.”
Willy Twiston-Davies enjoyed a red-letter day as Primitivo gave him a first Royal Ascot success in the King George V Stakes.
Twiston-Davies’s family are steeped in the National Hunt sphere, with Gold Cup and Grand National-winning trainer father Nigel and leading jockey brother Sam renowned names, but now the younger Twiston-Davies has scored a first.
Trained by Alan King, who was also enjoying an inaugural victory at the Royal meeting, Primitivo came full of running well over a furlong out.