Kerrin McEvoy took the race in hand from the jump and dictated from the front, kicking clear in the straight to defeat May’s Dream and Gregers.
The victory continued a terrific week for trainer Peter Snowden and the Darley team after a big-race double with Long John and Complacent at the weekend.
Snowden now has another decision to make regarding where to head with their top team of three-year-olds.
He has maintained now is the best time to send Guelph for a break and not push on into the spring and a possible start in the Cox Plate.
He already has Long John in the race after the team decided to give the Caulfield Guineas winner his chance in the weight-for-age championship on October 26.
Like the decision with Long John, Snowden says the team will take the next day or two before deciding their filly’s immediate future.
“It’s not my call alone, it’s a team decision,” he said.
“I’ve made it known all along that I’d like to stop with her now, but the boys will have a talk and chat to the boss (Sheikh Mohammed) at home to see what his thoughts are, but we’ll come up with the right decision I hope.”
“The horse has to tell you … what we want and what they can do may be two different things.”
It has been an outstanding week for Snowden and Darley, who also prepared Derby contender Complacent to win the Spring Champion on Saturday only hours before Long John’s victory in the Guineas.
Guelph’s dominance was evident in betting for the Thousand Guineas, for which she was sent out a $1.45 favourite.
It makes her the shortest-priced favourite to win the race in the modern era ahead of the likes of Alinghi, Miss Finland and Atlantic Jewel.
“I had a few scenarios in my head behind the barriers, but when she began well I thought I’ll take the race by the scruff of the neck,” McEvoy said.
“It’s pretty arduous down that side, that wind is bloody strong and it does blow them off stride, even a big filly like her.
“It’s a nice prize for her for sure.”
Guelph, twice a Group One winner at two, is the first filly to win the Flight Stakes-Thousand Guineas double since Dashing Eagle in 1996.