He recorded the best round of the crucial final day at the Apulia San Domenico Challenge Tour Grand final.
He began the day right on the brink of missing out on a ticket to the elite of European golf after a level par third round of 71, and the pressure was on to secure any sort of card for The European Tour.
But his star show on the final day, which gave him a tied sixth finish five shots behind winner Andrea Pavan on 12 under, meant he secured a top 15 place and a top tier category for next season.
The 34-year-old was already celebrating before the final round began after his wife, Ciara, gave birth to their second child, a baby boy, on the evening before the third day, but laughed off suggestions that he might decide on‘Dominic’ as a name in honour of the course where he sealed his European Tour card.
“I haven’t got a name for my son yet,” said Thornton.
“I would like to dedicate that round to my son though, I thought something was going to be good after the third day when I played well, but then got tired.
“But when the wind picked up today and it was in my favour.
“It was looking tight for a while (to get into the top 20). I tried not to think about where I was but I read a little piece on the European Tour website so thanks to whoever wrote that!
“I felt horrendous on Friday though (with an illness), so to get through that and still get the card was great.”
The England-born player’s fairytale round started with a steady par on the tough first hole before a birdie on the third was soon followed by three consecutive birdies on the fifth, sixth and seventh to see him reach the turn with a four under par 30.
Only one birdie followed on the way home, but his piece de resistance came at the par five 11th, where his three wood approach from the fairway fell to within ten feet before holing the putt for a superb eagle.
Home hero Pavan, meanwhile, edged his final day shoot-out with Tommy Fleetwood, but it was the young Englishman who ended the season as the Challenge Tour Rankings Number One, becoming the youngest winner in the 22-year history of the Tour.