The son of Elzaam, owned by Chloe Baines, was backed up quickly following his good sixth in the Windsor Castle Stakes at Royal Ascot and had little trouble landing the spoils.
He was settled on the heels of the leaders by Jack Mitchell and travelled smoothly throughout.
Once they turned for home, Jack pressed the button and Pretty Vacant picked up well, scooting clear to win by two and a quarter lengths.
Roger said: "He had been in great form since Ascot so we decided to take our chance here. It was a straightforward win and he is a speedy two-year-old with plenty of talent."