The pair pulled clear on the stands side as the field split into two groups, but it was Henry Cecil’s Jacqueline Quest who prevailed by the narrowest of margins.
However, a stewards’ inquiry was called after Cecil’s filly drifted into the middle of the track, taking the French challenger, ridden by Stephane Pasquier, with her.
After around 10 minutes, the stewards declared that the 9-2 favourite had been awarded the race, to give trainer Criquette Head-Maarek a fourth success in the fillies’ Classic.
Special Duty was drawn in stall one, with Cecil’s filly in stall four, and those drawn low had a discernable advantage.
Jacqueline Quest hit the front two furlongs out, but the favourite made eyecatching progress and gained a slender margin inside the final 100 yards - only to seemingly lose out by a nose.
However, the 66-1 winner drifted markedly from a straight line and the placings were reversed because the winning margin was so narrow.
Jim Bolger’s Gile Na Greine finished third at odds of 25-1.
Head-Maarek said: “Stephane said had the other filly not pushed him over, he would have won easily – but she (Jacqueline Quest) was drifting all the time.
“I don’t like to win races like that and I feel very sorry for the others.
“I think they (the stewards) were right to do that, but I didn’t think they would.”
Head-Maarek added: “It is fantastic that both Guineas have been won by the French, but I don’t imagine the British will see it like that.”
A philosophical Cecil said: “I’m pleased she ran so well – it’s one of them things.
“She ran really well. I wasn’t sure she’d stay a mile but she’s improving.
Stipendiary steward William Nunneley said: “Obviously there was interference and you could see Special Duty had been taken across the track by Jacqueline Quest – we had to decide whether it affected the result.
“The winning distance was a nose and she (Special Duty) was taken nearly halfway across the track. We had to decide if they had both stayed straight, would the result have been the same?
“We decided that it obviously cost her more than just a nose so we had to change the places around. When you have such a short distance between two horses and they have gone so far it is not a difficult decision and we had to make it.”