The 32-year-old Englishman started Sunday's final round seven strokes off the lead at The Belfry but made nine birdies — including four on his last six holes — to finish the week on 14-under par and move into the lead with the late starters still having holes to play.
No one could catch him, with four players — Nacho Elvira (69), New Zealand's third-round leader Daniel Hillier (73), Niklas Norgaard (71) and Jakob Skov Olesen (71) — tying for second place, three shots back.
This was the first tournament in Team Europe's qualifying process for next year's Ryder Cup, so that's suddenly an unlikely target for Dean — quite the turn of events for someone who spent time delivering groceries during the COVID-19 pandemic in 2020.
He kept doing the job for nearly four years to help fund his career when he didn't have a card.
"I enjoyed it for most of the time," Dean said of his old part-time job.
"Obviously it's a completely different life, a completely different lifestyle. I still see the vans going up and down the road every now and then, and I keep in touch."
It was a family success, too. Dean got married to Emily following the British Open in July and she was his caddie this week.
"I can't thank her enough for what she has to put up with, with me," Dean said.
"It was bad enough off the course, with the lows and stuff. Now it's on and off the course. I hope I made her proud."
Marco Penge tied for sixth place with a final-round 72, marking a solid start to Ryder Cup qualifying after he failed to get selected as a captain's pick two years ago in a breakout season on the European tour that contained three wins.
Penge acknowledged this week it was the correct call by captain Luke Donald, whose team went on to win 15-13 at Bethpage Black.
