The daughter of Holy Roman Emperor had run better than her finishing position suggested in both the Albany Stakes at Royal Ascot and the Cherry Hinton at Newmarket and has improved with every start.
Running his first-time blinkers she made every yard of the running under Andrea Atzeni and went on to score impressively by two lengths.
Roger said: "We have run her in nice races because we think she's a nice filly but the only place to judge a horse is on the racecourse and she hadn't quite come up to this level in the Albany and Cherry Hinton, which means she didn't really warrant being a shorter price.
"She isn't in any way ungenuine but I think the blinkers helped her to focus."
Andrea added: "She travelled really good today, two out she was going so well I knew I'd win. The blinkers appear to have done the job as she was much sharper today and she quickened well."
Princess Noor (nearside) works on the Watered Gallop