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."
Saeed bin Suroor and Danny Tudhope combined to win the Wolferton Stakes with Dubai Future.
Fourth behind leading Prince of Wales's Stakes contender Bay Bridge in the Brigadier Gerard Stakes at Sandown last month, the six-year-old looked far more comfortable stepping down to Listed class.
He loomed up travelling strongly early in the home straight before kicking clear, with 11-2 favourite Cadillac – who changed hands for £500,000 at the Goffs London sale on Monday evening – beaten three lengths into second place.
Bin Suroor said of his 20-1 victor: "The jockey gave him a very good ride. I just told him to keep him calm nice and relaxed in the race, he was travelling good and he finished his race well.
"The cheekpieces keep Dubai Future more focused and now we'll go for the Group Two at Newmarket – the Princess of Wales's Stakes."
Tudhope completed a quickfire double in the concluding Copper Horse Stakes aboard the David O'Meara-trained Get Shirty at 16-1..
Already successful at Thirsk and Hamilton this season, the six-year-old burst through against the far rail to beat Chester Cup winner Cleveland, the 2-1 favourite, by a length and a quarter.
O'Meara said: "This is brilliant. He is a horse who has done nothing wrong this year. He is three wins from four starts. He got beat at Ripon by a horse in Rajinsky who was then third in the Chester Cup, so his form was there. Danny has given him a brilliant ride.
"We've had some Royal Ascot winners over the years with the likes of Lord Glitters, but they are hard to come by and they are all very much appreciated."
He added: "You would like to think he would be a stakes horse. The last good horse I had like that was Blue Bajan. I'm not sure he is up to that level yet, though.
"We bought him from France quite cheaply. A couple of runs at the end of last year were not so good, but he has come out this year and had done absolutely nothing wrong and is three from four – it is absolutely brilliant."
