But while many at Newbury had joined in a late gamble to send Diamond Harry off at 6-1, an even greater ovation was reserved for Denman, who was not able to create history with an unprecedented third win in the famous handicap but heroically carted 11st 12lb to finish third.
The presence of Denman pushed all but a handful out of the weights and the fact Diamond Harry was carrying almost 2st less became obvious from some way out, with Daryl Jacob sitting motionless in the saddle even at the critical moments in the home straight.
Diamond Harry was always coasting at the front and when the giant effort required by Denman proved too much for him to bear, it was Burton Port who jumped out of the pack to challenge.
But Jacob always appeared to have a little more up his sleeve, finishing a length-and-a-quarter clear, with Sam Thomas and Denman a further 14 lengths in arrears.
Diamond Harry has dazzled in bumpers, novice hurdles and chases but had fallen notably short on a couple of occasions at the Cheltenham Festival – where he must yet return for the Gold Cup next March.
"I know I probably don't look like I'm happy, but I am!" said Williams, who values quality over quantity with only around 30 choicely-bred sorts at his stable at South Molton in Devon.
"We've won some decent races before, and we've got some nice horses but this is a step up."
Williams diverted much of the credit to his wife Jane, who does much of the hands-on work while he concentrates on poring over the formbook.
"Jane does the training and I do the placing," Williams added.
"The horse has changed a lot in the last six months and he has a fantastic record at the track, so I thought he had as good a chance as any here. Coming into the straight I could see that Daryl hadn't moved and he looked confident all the way through the race. I would have been astounded if anything had got past him from three out. He's not an obvious Cheltenham horse but we are going to have to look at the Gold Cup.
"He won't run in a whole lot of races now. We entered him in the Lexus Chase and he was probably going to run there if he was placed, but that's not out of the equation yet.
"Otherwise there is the option of going back to Cheltenham for the Trials meeting."
Jacob dedicated this victory, as he does every one he rides, to his late friend Kieran Kelly, the talented jockey who suggested he moved to Britain many years ago.
"There was 2st difference between us and Denman and if ever we were going to beat him, it had to be today," said the Irishman.
"It was an amazing effort from Denman, he was still with me up to the second-last fence and all credit to his trainer Paul Nicholls.
"But I sat on him during the week and I said to Nick I'll never ride a horse like this again.
"I couldn't have asked for a better ride – he jumped, travelled and did everything I wanted him to do.
"He's a young horse and still unexposed. The Gold Cup is a long way off, he was getting a lot of weight and was entitled to win on his hurdles form, but we can dream can't we?"
Nicholls was noticeably moved by the appreciation of Denman, with the 4-1 favourite and former Gold Cup winner roared on by the crowd when he moved into contention even on the back straight, and again when he returned to be unsaddled.
"That was an outstanding run at the weights and I always thought Diamond Harry would be very hard to beat if he jumped," said Nicholls.
"Nick Williams is a great trainer and Daryl is a brilliant jockey and you have to congratulate them.
"The ground was just a bit lively for him and he was flat out all the way, but that has got to be one of his career-best performances.
"I've had a chat with Sam and because he's best fresh, we're going to give him a break now and go straight for the Gold Cup.
"This is why jumps racing is so popular, the horses keep coming back and races like this are so good for the sport."
Nicholls also had the respective fourth and fifth home, The Tother One and Niche Market, and said they had run "cracking Grand National trials".
Barry Geraghty was a little disappointed not to have won with Burton Port.
"He hit the cross-fence five out and although he picked up again, the other horse was always finding a bit more and I think we had run our race by then," said Geraghty.
Irish raider Pandorama was pulled up early on and only 10 of the 18 finished.