Coltrane provided apprentice jockey Callum Hutchinson with his first taste of Royal Ascot success with a battling display in the Ascot Stakes.
A field of 19 runners went to post for the two-and-a-half-mile handicap, with Bring On The Night the 3-1 favourite to provide Willie Mullins with a fifth victory in the race in the last decade.
A neck runner-up to Cleveland in last month’s Chester Cup, Coltrane (14-1) was guided to the lead inside the final two furlongs by his 5lb claimer, who punched the air as he saw off the challenge of Bring On The Night and Ryan Moore by three-quarters of a length.
Arcadian Sunrise made late gains to finish the same distance further back in third, with Going Gone fourth and last year’s winner Reshoun in fifth.
Winning trainer Andrew Balding said: “I was happy at every point, Callum gave him a great ride. He was always where he needed to be and he found space, even when the other horse looked like he was going to come to him.
“I’m very proud of the jockey and of the horse. Five pounds can make a big difference at this trip and Rob (Hornby) was claimed by Ralph Beckett to ride his horse.
“It’s a hot day and it might be a bit too much to ask to come back for the Queen Alexandra (on Saturday). He’s won a Melrose so the Ebor is possible, there’s are plenty of options.”
A delighted winning rider added: “I can’t put it into words! A big thank you to the boss and to the Mariscottis (Coltrane’s owners) for giving me such a great opportunity.
“The boss has been a great supporter this year and I’ve ridden six winners from 17 rides for him. He’s been great to me, and I’ve been kicking on throughout the year. Hopefully this winner will give me a real kick and the season will keep on progressing.
“This horse is a big yard legend and I’ve ridden him a fair bit at home. People come in and out and he’s the one they get to sit on – he’s just a brilliant horse to have.
“My mum and my nan are here, so they’ll be delighted to see that. Obviously my dad was a jump jockey and rode multiple Grade One winners, so that was something I wanted to do, although he never rode at Royal Ascot.”