Twiston-Davies, who has won the Grand National twice - with Earth Summit in 1998 and Bindaree four years later - had a perfect build-up to the big race as the focus centred on the two favourites, neighbours at the Somerset stable of champion trainer Paul Nicholls.
"I loved all the Kauto Star/Denman thing. I was the forgotten man but I always thought we could beat them," said the 52-year-old.
"Paul Nicholls has done a wonderful job with the two horses but we need new horses coming through and ours is the best now."
Imperial Commander had won the Ryanair Chase at the Cheltenham Festival in 2009 and gave Kauto Star a scare in the Betfair Chase at Haydock in November when he was ruled to have been beaten by a nose in a photo finish.
Twiston-Davies felt his horse should have got the verdict then, but he made no mistake this time for the man who trains at Naunton, about 12 miles from the track, and who will celebrate at his local pub The Hollow Bottom.
"Kauto Star was in trouble a long way out, he wasn't the horse he normally is. Denman didn't run well the time before and as soon as Kauto Star was beat, I thought it was ours," he said.
"Everybody was talking them up and wearing their green scarves, nobody looked at us with our black-and-white scarves."
The winning scarves are a bow to a couple of Newcastle United supporters who are part of the six-strong syndicate, called Our Friends in the North, who own the horse.
Imperial Commander cost £30,000 for them to buy, roughly a 10th of the purchase price of Kauto Star, who has won 13 Grade One races and a record four consecutive King George VI Chase victories in a sparkling career.
Brennan and Pigeon Island completed a treble for the Twiston-Davies team
The syndicate, which numbers the wonderful name of Hugh Doubtfire among its clan, has known difficult times, with the death of promising hurdler Bobby Dazzler a few years ago.
They used the insurance money to buy Imperial Commander and what a dazzler he has proved to be - his shock win earning his owners nearly £280,000.
"I came here with my father as an 11-year-old when The Dikler won [in 1973] and I said one day I'd win a Gold Cup," said Carlisle-based syndicate leader Ian Robinson.
"He laughed at me and that spurred me on. I wasn't sure how I was going to do it, I was too big to be a jockey so this is just a dream. There's never been a happier bunch of owners."
In 40 minutes that will take some beating, Twiston-Davies held court with the assembled journalists as the Gold Cup press conference turned into a commentary on his 17-year-old son Sam's victory on Baby Run in the following race, the Foxhunters' Chase.
The bold teenager led from the front, and his proud-as-punch father punched the air with delight and leapt for joy, having given a running commentary on the race. Oh, Nigel owns the horse as well.
Asked which victory gave him the greatest pleasure, the trainer said: "To be dreadfully honest, it would have to be the Foxhunter. I'm hugely proud of Sam.
"Having my son win is brilliant. He's got another year at school, so there's no rush to think about whether he'll go professional one day."
Behind Imperial Commander were two sterling performances as Denman finished runner-up for the second year and Mon Mome claimed third at 50-1 nearly a year after winning the Grand National at 100-1.
Denman's joint-owner Harry Findlay was gracious in defeat and eyed a tilt at the Grand National in 2011 with the horse who has the heart of a lion despite a heart murmur which nearly ended his career.
"He's shown so much guts there. It was a great race, great for the public. If he's not a National horse, then I'm blind," said Findlay
Tony McCoy, who rode Denman, added: "Second is better than third and better than Ruby [Kauto's jockey Walsh] ended up with."
Gold Cup was never a two-horse race - Twiston-Davies
Walsh, who chose to ride the 8-11 favourite ahead of Denman, fell four out but had done well to stay on his mount earlier after a blunder at the eighth fence.
"It is always a relief when a good horse like him gets up and is OK," said Walsh, who could well go for an historic fifth King George win on Kauto at Kempton Park on Boxing Day.
"He's alright, I'm alright - there will be another day. It is disappointing, but it is not the end of the world."
It may have felt close to the end of the world for some punters as the surprises continued in this Festival of the long shots.
Twelve months ago, owner Clive Smith was "Mr Lucky" after his brilliant two-miler Master Minded claimed a second Champion Chase and Kauto doubled up in the Gold Cup.
They both returned a year later as odds-on favourites, and both failed to make the frame. What were the odds on that, I wonder?
And just to prove that when your luck is in, it is well and truly in, Brennan rode 16-1 chance Pigeon Island to victory in the Grand Annual Chase, the last race of a meeting where only four favourites won from 26 races.
That completed a 747-1 treble for Twiston-Davies. Flying high like a 747 aeroplane.
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