Cheltenham hails young amateur jockey as he guides Nicky Henderson's horse to glory

Free with his time throughout the build-up, Mr S Waley-Cohen appeared on Channel 4's The Morning Line before the Gold Cup and was asked: "Is this the biggest day of your life?" A smile crept across the face of Long Run's amateur rider. "I wouldn't say that," he said. "It's a big day, but not the biggest of my life."

Seven hours later, Sam Waley-Cohen, 28, found himself tucked in behind the two great champions of recent steeplechasing history, Kauto Star and Denman, as the trio turned for home in a race that will be remembered for a kind of perfect symmetry. The two equine luminaries were passed by the new horse on the Cotswold block – the youngest Gold Cup Champion since Mill House in 1963, and the first to be ridden by a part-timer since Little Owl and Jim Wilson in 1981.

The beauty of this contest lay not only in Long Run's graduation but the grandeur of Kauto Star and Denman in defeat. This was not a smashing of the old order, but a dignified and thrilling exhibition of Long Run's youth and energy, even if Imperial Commander, the defending champion, pulled up lame.

In the saddle, Waley-Cohen proved a young sportsman can thrive in this forbidding arena without having to sign his whole life away to the weighing room.

It was not the biggest day of his life, and that is what made it special.

Even in the media conference afterwards, he kept one eye on a television screen showing the next race, the Foxhunter Chase. Life was moving on already. Soon Waley-Cohen will be back at the day job, fielding the 150 emails he receives each day as the head of Portman Healthcare, a firm he set up to revolutionise dentistry.

On Sunday in an interview for the Observer, Waley-Cohen said: "Ultimately it's about doing it for fun. Not making your living out of if it. It doesn't mean being amateur in the sense of amateurish. There isn't really any space for amateurism in any sport any more. So you have to take a professional approach even if you're doing it for the fun. Doing it because that's what you want to do; getting out of bed thinking, 'Why not?' That's a cracking way to spend your time, as opposed to thinking, my percentage is X amount."

He thinks about this a lot. He has to because people keep asking him about Corinthianism. In this golden age for jump jockeys he was up against a mobile hall of fame: AP McCoy, Ruby Walsh, Richard Johnson and Robert Thornton, for starters. In the race no special privileges were extended to the gentleman rider. On the contrary, the hardened pros appeared intent on spooking him into submission.

"He gave the horse a beautiful ride and a brave ride," said Long Run's trainer, Nicky Henderson. For it was no procession. A radiant beast, the new champion clouted two fences on the first circuit and had Waley-Cohen worried before the pair regained their poise to hunt the two Paul Nicholls-trained warriors down the hill and into the straight.

"It's surreal sitting here. You can barely believe it," Waley-Cohen said. "Several times I thought, 'This is not how I imagined this going.' I didn't know whether I was coming or going at some of the fences. You go into them and throw everything at them, your heart, your soul and your guts.

"Everyone from the point-to-point and amateur worlds has been so generous. There has been such an upswell of goodwill and I could almost feel them willing me on. Not many amateurs have been lucky enough to have a go in this race. It came down to stamina, not speed, and Long Run had the courage and youth to get up that hill. It was do or die at some of those fences. You'll be eating grass if you don't pick up."

In the final surge there was little to distinguish Waley-Cohen from Sam Thomas (Denman) or Walsh (Kauto Star), except perhaps slightly less rhythm and a touch more stiffness as he drove Long Run towards the wall of noise.

On his saddle were the initials of his late brother, Thomas Waley-Cohen, who lost his life to cancer, aged 20. "It's a great family event, and Thomas would have been very much here," Sam said, not wanting to delve too deeply into the family's emotions during this part private, but mainly public spectacle.

This was an object lesson in how to handle a big moment, a precious opportunity. Waley-Cohen worked hard in the gym, rode work at dawn, studied the tapes and made himself available to all those in the media fascinated by his adventure.

The pair won the rescheduled King George VI Chase at Kempton, spoiling Kauto Star's script, but this was on another scale, especially as Long Run hardly ever jumps steeplechase fences at home and is schooled indoors.

A committed thrill-seeker who escapes the stresses of business life by climbing mountains or piloting helicopters, Waley-Cohen is cool in the face of physical pressure, as if he knows none of it really matters anyway, and can only be spoiled by taking it too seriously.

"Racing is poetry. It has jealousy and ego and greed and compassion – and loyalty and glory," he said in the Observer. "It encapsulates life from victory to defeat, and life and death, all those things, and yet when you step back from it you can't take it to a point where there's no return."

This is not the usual post-race testimony. Normally, the winning jockey is a bony addict with the narrow vocabulary of obsession. Waley-Cohen liked where the Gold Cup took him but he has plenty of other worlds to inhabit.

"It's rough out there," he said. "The Gold Cup is a war. A brotherly war, but nonetheless a war, where there's no quarter given." No quarter given, and none asked.