Frodon and Bryony Frost sprang a 20-1 shock to win the Ladbrokes King George VI Chase at Kempton.
Frodon, previously successful under Frost at this Grade One level when they won the Ryanair Chase at the Cheltenham Festival last year, was delivering a 12th success in the Boxing Day showpiece for trainer Paul Nicholls.
To do so, they had to see off three better-fancied stablemates in Clan Des Obeaux - seeking his King George hat-trick - Cyrname and Real Steel.
Frost dictated a steady pace throughout - and as her rivals dropped away one by one, they repelled the field from the front to win by two and a quarter lengths and six lengths from Waiting Patiently and 85-40 favourite Clan Des Obeaux.
Frost and Frodon had been beaten more than 80 lengths in their last race at the start of this month - when, to the brilliant jumper's detriment, several fences were omitted because of a low sun at Aintree.
The eight-year-old was back in his element here, however - and so too Frost.
On pulling up, she told ITV Racing: "We've just won the King George!
"I have had the absolute best time going round there on him.
"The dark days, the hard words you get thrown at you, to gallop round there with him ... he has just smashed everybody's expectations.
"He's gone round a track that's the wrong way for him, always giving away ground a little bit at his fences.
"I got some amazing jumps from him. He's what you dream of as a little girl - absolutely epic."
Frodon was not first away from the tapes, but was still in front by the first fence.
"Down at the start, he was a bit of a monkey," Frost added.
"But he set sail over the first couple, got his lead. The pressure from Santini the whole way made me nervous - but I got a few breathers.
"(Then) I was thinking 'how many more fences have we got to go? Where's our line?'
"I could not believe it. I had to double-check myself that I didn't have to go round again."
Nicholls admitted his surprise that his 12th King George had come with the outsider of his four runners.
"It's amazing - although obviously he's a very good horse on his day," he said.
"He loves it round here, and I just said to Bryony 'just go as quick as you can, keep galloping and sail on - you know he's tough and brave'.
"I think he took the mickey out of us a little bit the other day, when he didn't have those fences, and he came back really fresh.
"I've done some serious work with him since, and he thrives on it.
"You've just seen today what a remarkable horse he is. He never knows when he's beat!"