The Giant's Causeway colt was a warm order in the betting following his recent second at Wolverhampton and duly obliged under Jamie Spencer although he did provide some hair raising moments.
Horsted Keynes showed his inexperience again, racing freely which forced Jamie to settle him futher towards the rear than he would have liked.
He picked up well to hit the front with half a furlong to run but then his greeness showed again when he idled but managed to hold the runner-up by a neck.
Roger said: "Horsted Keynes did plenty wrong but still managed to win. He would have preferred a better pace to run at but he has got the job done."
Earlier in the evening, One Pekan had run a pleasing debut to finish third, also over 7f at Kempton.