Hollie Doyle followed up the victory of Trueshan in the opener at Ascot by landing the first Group One prize of her career aboard Glen Shiel.
Archie Watson's charge has transformed of late and having broken smartly in the QIPCO British Champions Sprint Stakes, he set out to make all the running.
The six-year-old looked set to be swallowed up at the furlong pole when headed by the strong-travelling Oxted, but with Doyle at her strongest and her partner very willing, they rallied bravely and then fended off the late thrust of Brando by a nose in an epic contest.
One Master (11/2) was another to finish well in third with Art Power (7/1) fourth.
Doyle said: “I’m in a state of shock right now. I didn’t think I’d won, so to have had the result we have was incredible. We had a good old battle with Oxted from the three-pole and I thought that I would be doing well to hold on like I did, but he is such a game horse.
“He is incredible. He has got quicker with age. When we first got him, he was running over 10 furlongs in France and didn’t show a whole lot of speed, but the further we dropped him back, the quicker he has got.”
She added: “It’s not about me it’s about Archie Watson, he has campaigned this horse unbelievably. No one else would have won a Group One with this horse.
“It is a dream come true, a massive dream come true, especially on this horse. Everyone in the yard adores him. My aim at the start of the year was to ride a Group winner and I always said a Group One one day, but I didn’t think it would come this year.
“I don’t get too carried away, but I’m a bit delusional as to what is going on at the moment as it has all been a bit of a whirlwind. It has been a great few years.
“It feels really unusual as for someone like me it doesn’t normally happen, but it has done today.”
The Kevin Ryan-trained Brando was ridden by Tom Eaves, who said: “He has run a stormer. You are always gutted finishing second, but he has run a great race. It was a bob of the heads. I’m delighted, but gutted at the same time.
“He has been running OK. He ran well at York last Saturday and that probably put him right. York has never been his sort of track. He likes it here on this big, stiff track. It is a great training performance.”