The son of Lope de Vega, who was successful in the Dewhurst Stakes as a two-year-old, quickened two and a quarter lengths clear of Calling Out having travelled sweetly under James Doyle.
Custom Cut set particularly modest early fractions in soft ground, but Belardo settled nicely in third before challenging between horses inside the two-furlong marker, the result never being in doubt thereafter.
Owned by Prince A A Faisal and Godolphin, Belardo showed top-class form at three having finished runner-up to Solow in the QEII at Ascot.
Roger is hopeful he can make a further impact in the top table later in the season, with a tilt at the Group Two Sandown Mile a potential next target.
He said: “I was a bit worried two furlongs out as he was boxed in, but as soon as they started to split it always looked like he would win.
“His work has been excellent at home, we targeted this race a long while ago and I am delighted. I need to talk to the owners but I would like to take him to Sandown for the Sandown Mile.”
The stable notched a double on the day courtesy of Ennaadd in conditions company over a mile at Kempton.
Sheikh Ahmed Al Maktoum’s three-year-old built on his last-time-out victory in a Chelmsford handicap by getting up late under Andrea Atzeni, who was registering his fourth victory on the afternoon.
Roger said in the aftermath: “Ennaadd is thoroughly progressive and I was pleased with how he knuckled down in the closing stages. They didn’t go particularly quickly but he is a colt with a smart turn of foot. He deserves a crack at something better now.”