It was arguably the most famous season in Formula 1 history, featuring thrilling racing, off-track controversies and the near-death of the sport's most famous driver, Niki Lauda, as he battled James Hunt for the world championship.
Through the long, hot summer of 1976 Hunt's attempt to claw back a huge points deficit to reigning champion Lauda was big news in Britain.
The season was so dramatic it inspired director Ron Howard to make the 2013 film Rush.
However, almost the entire season - including the British Grand Prix - was not broadcast on television in the UK because one of the cars was sponsored by a condom manufacturer.
BBC Sport tells the story of how a forward-thinking contraception company led to an F1 blackout, as the sport draped itself in cigarette advertising.
'Totally unacceptable for family viewing'
Forty years ago, moral standards and sensitivities were different in Britain, while levels of advertising on TV, particularly in sporting events, would often be a source of angst.
Jonathan Martin, who was a producer on BBC's Sportsnight in '76 and would go on to create the Grand Prix programme two years later, says that F1 "already had a special place" because "broadcasters had to tolerate" on-car advertising, while "in many other sports it was invisible".
After all, on-shirt advertising was not allowed in televised league football matches in England until 1983.
In '76 not all F1 races were televised in the UK, with coverage generally focused on glamour events such as Britain, Monaco, Germany and Italy.
But these would all be blacked out when John Surtees signed a sponsorship deal with the London Rubber Company, which would see his team's main F1 car emblazoned with the Durex brand.
The tipping point came at the non-championship Race of Champions at Brands Hatch in March, which the BBC was due to televise with Murray Walker commentating.
In his autobiography, Walker recalled: "As far as the BBC was concerned a visible Durex logo was totally unacceptable for family viewing.
"I arrived at Brands Hatch to be greeted by producer Ricky Tilling with the words: 'Hi Murray, we'll know by 11am whether we're going to be on air or not.'
"'What are you talking about, Ricky?'
"'Durex. We're not going to transmit the race unless Surtees agree to take it off their cars.'"
They did not, so the BBC packed up their cameras and left.
'It was done in a very wholesome way'
Surtees, the only man to win the world championship in F1 (1964) and on 500cc motorbikes (1956, '58, '59, '60), had set up his own team in 1970 but they struggled at the top level.
Finance, or the lack of it, was always an issue so it was almost a lifeline when the team was approached by the London Rubber Company with a sponsorship proposal "offering a decent sum of money".
Surtees recalls: "I said to them we would have to sit down and do it in a very wholesome and presentable way.
"I thought it would cause a stir but the fact remains that there was nothing sleazy about it and we weren't breaking any rules.
"It revitalised the team and gave it a second chance."
According to Martin, the Surtees sponsorship "caused a flurry at management level" at the BBC and ITV, who also broadcast occasional F1 races at the time.
"Grand prix racing already had a special place and then when Durex appeared on the side of a car, there were certain apoplectic people around," he said.
Conflict and argument never far away
F1 in 1976 was all about Hunt and Lauda, the flamboyant British playboy and the methodical but brilliant Austrian. Although the two men got on well, conflict and argument was never far away.
Lauda had a 26-point lead when the cars went to Brands Hatch for the British Grand Prix in July but Hunt had won the previous race in France and had his points for finishing first in Spain reinstated after he had initially been disqualified.
A record crowd descended on the Kent circuit on a scorching day to roar Hunt on, but it appeared that his race was over when his McLaren was damaged in a first-lap crash that caused the race to be stopped.
Stewards looked to set stop Hunt from taking part in the restart because he had not completed a full lap of the track when the original race was red-flagged.
However, they soon changed their minds when the restless, sun-burned crowd began to slow-handclap, chant "we want Hunt" and throw missiles onto the circuit.
Cheers erupted when Hunt appeared on the grid and they were even louder when he won from Lauda to cut the Austrian's lead to 23 points.
The only TV coverage of the race in Britain was a short film shown on ITV's World of Sport a week after the event.
Two weeks on from Hunt's home win, Lauda almost died when his Ferrari exploded into flames in a crash at the notorious Nurburgring in the German Grand Prix. He suffered horrific burns, damage to his lungs and was given the last rites.
The Austrian survived and incredibly was back racing six weeks later at the Italian Grand Prix, by which time his championship lead was only two points over Hunt.
The press and the public were rapt. But, the short Brands Hatch film aside, British TV continued with its unofficial boycott of F1.
'The management climbed down very rapidly'
Lauda extended his championship lead to five points when Hunt spun off in Italy and the game appeared up when Ferrari's protest against Hunt's Brands Hatch win was upheld and the Briton was disqualified. The gap was now 17 points with three races to go.
But Hunt won in Canada and the United States, collecting 18 points while Lauda only managed two. It set up a showdown at the final race in Japan with the Austrian's lead down to three points.
At the BBC, it was time for a rethink.
"The Hunt-Lauda battle captured the public imagination," recalls Martin, who went on to become the BBC's head of sport.
"Especially when it went down to the last race in Japan, the management climbed down very rapidly off their social engineering stance.
"I was in the forefront of saying: 'Come on, we've got to go and do this' but I was helped in that by the fact that ITV were starting to think in the same way."
ITV had shown highlights of the penultimate race in the US and both broadcasters scheduled highlights of the Japanese GP.
Torrential rain in Fuji delayed the start and when it did eventually get under way, Lauda decided to retire after two laps as he considered the conditions too dangerous. Hunt splashed around the soaked circuit to finish third and take the title by a single point.
And, finally, British viewers were able to enjoy the drama.
'It was a fairly provocative thing to do'
Surtees, now 82 and still a keen follower of F1, says he was disappointed that the Durex sponsorship proved so unpalatable.
"It was purely a question of the BBC making their decision. From the point of view of the sport, I was very unhappy," he said.
"It was very important for the sport to be able to give a good platform for people to support it. It didn't make me happy that the BBC took that position.
"I thought it was ill-advised considering so many government agencies were out there pushing these products."
Martin, who says the interest generated by the Hunt-Lauda battle was the reason he suggested to BBC management that they should cover every F1 race from 1978, can see both sides of the argument.
"With hindsight, it was a fairly provocative thing to do. He was within his rights to do it just as the broadcasters were within their rights," he said.
"I think it pushed the broadcasters to the limit because F1 already had special dispensation compared with many, many other sports."
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