Punters who backed Quickthorn's rivals were left frustrated as the stayer turned the Weatherbys Hamilton Lonsdale Cup into a procession.
Tom Marquand obtained a big lead early on and their York rivals were never within striking distance. The Group 2 had earlier lost its lustre when the big two, Stradivarius and Trueshan, were taken out.
But Quickthorn stamped his authority on the field with the all-the-way performance, crossing the line 14 lengths ahead. Marquand was quick to deflect praised for his inspired ride to Quickthorn, who returned at odds of 9-4 in the betting.
"I wouldn't say I'm brilliant for that," the jockey told ITV Racing.
"He's really coming to the fore as a top stayer. He goes round in that slightly exuberant fashion. When he won in France (on July 14), I came back in and said I had another two gears up my sleeve!
"After a little bit of time you're thinking 'did I really? Am I kidding myself?'.
"He's got the most enormous engine and he's just really learning how to use it now."
Coltrane, the 5-4 favourite, edged past outsider Reshoun for second, ridden by superstar Baaeed's jockey Jim Crowley. Backers of those horses and the three other runners took to social media to air their views about the result.
"Joke of a race," one wrote on Twitter.
Another said: "All jockeys bar Tom Marquand need to explain themselves to the stewards and punters."
A third person added: "Enterprising from Tom but quite a dull watch otherwise."
Racegoers attending Friday afternoon's fixture were asked to consider dressing in the black and yellow colours of Stradivarius. The three-time winner of the race was due to try and make it four on the Knavesmire in another big showdown with Trueshan.
However on the morning of the race, John and Thady Gosden pulled the fans' favourite out when he was found to have a bruised foot.
That left old rival Trueshan clear at the head of the betting, until Alan King withdrew the mudlover too.
"I spoke to a good few jockeys and they were all adamant it (the ground) is drying all the time," he trainer said.
"It's too quick for me. We want to run him but you've got to look at the big picture. If we make the wrong call today and he comes back jarred we might miss the Cadran and Ascot. I'm sorry for everyone."
