Paddington will be bidding to put his York defeat behind him and go out all guns blazing, with trainer Aidan O’Brien admitting Saturday’s Queen Elizabeth II Stakes could be the colts last racecourse appearance.

The staggeringly progressive three-year-old started off his season with a commanding handicap success at Naas and few could have predicted the heights he would reach later on in his campaign. Aidan O'Brien's charge swiftly took the step up to Group 1 level in his stride with an emphatic success in the Irish 2000 Guineas, a performance that kickstarted a top-level four-timer with victories in the St James's Palace, the Coral-Eclipse and the Sussex Stakes all to follow.

His sole defeat of the season thus far came when third behind Mostahdaf and Nashwa in the Juddmonte International at York in August, but connections felt a hard campaign had caught up with him that day and subsequently, he's been off the track since.

O'Brien told Sky Sports Racing: "He's obviously had an incredibly busy season and turned up in every big race he possibly could have. He's an incredible horse really, so it was great for us to be able to give him the time and he really appreciated it, we think,"

"He loves racing and loves work. He's an unusual horse in that when you build up his work, he starts putting on weight, that's just the way he is. He loves hard work, and he thrives on it.

"He was very impressive in all his races, he's a good strong traveller and quickens very well and handles all types of ground. We're looking forward to seeing him out again."

The son of Siyouni did have the option of staying over a mile-and-a-quarter in the Qipco Champion Stakes, but O'Brien is confident the drop back to eight furlongs is the right move.

He added: "He goes like a real miler, even though he's won over a mile and a quarter. I think it was always going to be the QEII for him."

Paddington is generally 11/8 to regain the Group 1 winning thread and go out with a bang at Ascot on Saturday, with O'Brien suggesting this may well be the last time we see him on a racecourse.

"I couldn't see him staying in training as a four-year-old. He's a very valuable horse and a very wanted horse at stud, I'd imagine." O'Brien continued.

The John and Thady Gosden-trained Nashwa, who finished in front of Paddington when runner-up in the Juddmonte International at York, will also drop back to a mile following her third-place finish behind Auguste Rodin and Luxembourg in the Irish Champion Stakes at Leopardstown.

Nashwa will tackle the mile trip for the first time since producing an impressive performance to land the Falmouth Stakes at Newmarket in June and Imad Al Sagar's retained jockey Hollie Doyle is happy with the decision.

Doyle said: "It really hasn't mattered to me which race they chose.

"Nashwa seems just as good at a mile as a mile and a quarter, so the trip doesn't seem to be an issue, and she goes on any ground. She'd have had a right shout in either of them.

"She's been great lately when placed against the colts in the Juddmonte International and the Irish Champion Stakes, and those two runs have been close to her career best.

"Physically she does well year in, year out, and she's really stepped forward again this year. The figures say she's improved significantly again, which is mad, so I'm delighted she's staying in training."

French raider Big Rock will be hoping to break his Group 1 duck following a trio of consecutive second-place finishes at the top level this season. The son of Rock Of Gibraltar filled the runner-up spot in the Prix du Moulin at Longchamp last month and trainer Christopher Head has been happy with him since.

He said: "He has done some very nice work and everything's all right, he's a horse that has needed a bit of time between races and I'm very happy to have had that kind of break between the Moulin at Longchamp and the Queen Elizabeth Stakes. Heavy ground is not a problem."

Fellow French challenger Facteur Cheval posted a fine effort in defeat when conceding 7lb to Paddington on soft ground in the Sussex Stakes at Goodwood earlier in the season.

Trainer Jerome Reynier said: "All lights are green, the only question mark is the straight course as he's never been racing on one, but he handles the soft ground,"

"He was racing against Paddington in the Sussex, and he was carrying much more weight that day, it's always been the plan to angle the season around this race.

"We are happy, he is very consistent, and he is a lovely horse.

"We can only hope for the best, it is a very competitive race and it's very exciting to have a runner in what is probably the best race of the year.

"We don't mind any ground with him, he is such a consistent individual, and we are happy with the conditions.

"Paddington has had a bit of a rest and is nice and fresh, he and Big Rock are two horses that are ridden prominently so if we can keep up and follow them, that would be a good thing."

Star three-year-old filly Tahiyra looks likely to take her chance on the ground as she bids for a fourth-straight Group 1 victory following successes in the Irish 1,000 Guineas, the Coronation Stakes and the Matron Stakes.

2000 Guineas winner Chaldean will attempt to complete the Newmarket Classic and end-of-season mile finale double for the first time since his father Frankel in 2011. Andrew Balding's charge has been off the track since a disappointing performance in the seven-furlong Prix Jean Prat at Deauville in July but was previously a good second to Paddington in the St James's Palace Stakes at Royal Ascot.

Barry Mahon, racing manager for owners Juddmonte, said: "His work is very good, and Andrew and the team are very happy with him.

"In fairness to Oisin [Murphy, replaced by Frankie Dettori], he's been a great help the last few weeks riding him in his work, and everyone seems very happy with the horse.

"In terms of the ground, we know we handle soft ground, whether we handle heavy ground or not will be another question, but he's in very good form, he's had a good break and his form from earlier in the year is up there with the best of them.

"It's a top-class race, as you'd expect on Champions Day, and any one of them would be a plausible winner."