John and Thady Gosden edged into a narrow lead to become Royal Ascot’s leading trainers this week on the back of Coppice’s (6/1 JF) Sandringham Stakes victory.
The unexposed daughter of Kingman was making a winning handicap debut following a facile Newcastle novice success on her third career outing.
High numbers came to the fore once more and Frankie Dettori could be spotted travelling kindly with two furlongs to run.
The Juddmonte-owned filly had to switch for racing room but quickened up in the style of a horse that had plenty in hand to score convincingly by a length.
John Quinn's Breege (33/1) looked a threat entering the final furlong but could never quite get on terms with the winner while Rebecca Menzies filly Balalaika produced a career-best back in third to defy her starting price of 66/1.
Aidan O'Brien's frustrating day continued with Unless finishing back in fourth.
Dettori said: "That was a good effort and the Juddmonte team are here, including His Highness [Prince Saud Abdullah] and all the stud people, so to get a winner for them is amazing.
They have been great supporters of me going back to the filly Enable and other good horses.
"At one point we thought Coppice was a Guineas filly, but she didn't come to hand until too late, so we put her in this race thinking she would be competitive, and she was. We do think she will be a Group-race filly.
"I tracked the leaders, I got her settled, I got the splits when I wanted, and she did the rest. It was a very smooth performance, and, in these races, you don't usually get that.
"I love Ascot, I will miss it, but I'm enjoying the moment. I won my first Gold Cup in 1992 and 31 years later I ride another one, my ninth. It's been a good place for me and I've still got tomorrow."
John Gosden said: "Coppice is a sweet filly. She came unstuck in the soft ground at the Craven Meeting. We went to Newcastle to build her up, she won well.
We waited for the better ground, the faster ground – she came here fresh, and she has done it well.
He declined a run in the Coronation with the filly, saying: "I didn't fancy the Coronation... it looked rather an exceptional champion in there!
"This was very much where we wanted to come, we will sit down and work it out. There are various options."
The Kingman filly is a full-sister to 2018 Coventry Stakes winner Calyx and holds an entry in the Group 1 Falmouth Stakes.
