His preparations were unconventional, to say the least. He had spent the two weeks leading up to the race on a round-the-clock alcohol, weed and cocaine binge with his friend Barry Sheene, who was world motorcycle champion that year.
While Jackie Stewart famously abstained from sex a week before a motor race, Hunt would often have sex minutes before climbing into the cockpit.
He had a gigantic appetite for sex. Physically, he was unequalled even if, emotionally, he was, perhaps, an amateur.
In Japan, his playground of choice was the Tokyo Hilton, where every morning British Airways stewardesses were dropped off at reception for a 24-hour stopover.
Hunt unfailingly met them as they checked in and invited them to his suite for a party — they always said yes. It wasn’t unusual for him and Sheene to have sex with all of the women, often together.
But, as Stirling Moss, who used to carouse with Hunt in Monte Carlo before he was married, said: ‘If you looked like James Hunt, what would you have done?’
No one watching Hunt that week in 1976 would have believed he was preparing for the race of his life.
At the circuit, he had been behaving bizarrely — at one point dropping his overalls and urinating in full view of the crowds in the grandstand.
The spectators, many of whom had powerful binoculars trained on him, applauded once he had finished.
He waved back. Even on race day, his mind was on other things — and he didn’t care who knew it.
Nothing could have prepared Patrick Head, now co-owner of the Williams F1 team but then a young car designer, for the morning when he inadvertently walked into the wrong pit garage.
He found Hunt inside, with his racing overalls around his ankles, cavorting with a Japanese girl. Hunt laughed when he saw the interloper, who left, not quite believing what he had seen.
A few minutes later, Hunt left the garage and went around the side to carry out his pre-race ritual of vomiting — the result of extreme nerves combined with overindulgence.
Finally ready for action, Hunt went out to drive the race of his life… and won the 1976 world championship, beating his nearest rival by one point.
The televised action was seen by more than 30million people around the world and his victory signalled a huge celebration.
It was 24 hours before he was due to return to Britain and, in the interim, Hunt drank himself silly.
At a British Embassy reception in his honour, Hunt was so drunk that the ambassador hesitated to let him in.
The return flight on Japan Airlines had been block-booked by F1 boss Bernie Ecclestone’s travel company and was the scene for a riotous 12-hour party that drained the plane of alcohol.
When Hunt arrived back at Heathrow airport, 2,000 fans were waiting to greet him. He staggered down the steps of the aircraft, drunk, into the arms of his mother Sue and his beautiful, long-suffering girlfriend Jane Birbeck.
She had been seeing Hunt for nearly a year, but had no idea he’d bedded 33 British Airways hostesses and countless young Japanese fans during his two-week stay in Tokyo. But ‘bedded’ is probably the wrong word — there was rarely time to get them into bed, such were Hunt’s demands. He took his women whenever and wherever he could and slept with more than 5,000 in his lifetime.