Cool Ben Ainslie snatches fourth Olympic gold as rivals crumble in tense finale

His element is air, not water. The wind, not the sea. But in order to seal his status as the most decorated sailor in Olympics history, as he did with a fourth gold here yesterday, first and foremost Ben Ainslie needed fire. After all, he prised the laurels from Jonas Hogh-Christensen only on a medal race tie-break – and might never have done so, but for being provoked from his torpor by his Danish rival.

On Thursday, having finished behind him in six consecutive Finn races, Ainslie was infuriated when Hogh-Christensen and the Dutchman, Pieter-Jan Postma, accused him of touching a marker. Obliged to take a penalty turn, he came back seething. "They've made me angry," he said. "You don't want to do that."

Sure enough, Ainslie then harnessed the winds as though they were his own furies, closing the gap to leave things on a knife-edge yesterday. So long as they did not let Postma get too far ahead, whichever of the rivals finished first would win gold. In a failing, fitful wind, however, Ainslie doused his passions, summoned up all his experience and heeded the old axiom: "Don't get mad, get even." The 35-year-old beat only one of the other nine boats. In what was almost certainly his final Olympic race, however, it was the only one that mattered.

"I was angry at the situation," he said later, referring to the contretemps earlier in the series. "And I was on the back foot. Something had to change. But today was a strategy race, it was about making right decisions."

Actually, as much as anything else, gold ultimately proved contingent on sheer luck. In playing cat-and-mouse with Hogh-Christensen, Ainslie took a chance on Postma – and, in a fateful twist, could well have paid the price but for the Dutchman getting tangled with New Zealand's Dan Slater in a desperate late dash, and himself being obliged to take a penalty turn. Closing on second one moment, Postma had to settle for fifth, and so forfeited bronze to Jonathan Lobert of France.

Ainslie and Slater have been friends since adolescence, but nobody was reprising Ainslie's complaints on Thursday that Hogh-Christensen and Postma had "ganged up" on him. "All I wanted to do was protect the inside," the New Zealander said. "I said: 'Just don't do it.' It was a really big risk for not a lot of gain. He had silver sewn up."

Hogh-Christensen made a miscalculation of his own, electing to push his rival right in the opening stages only to discover that he had yielded him the favours of a capricious breeze. Ainslie was much quicker to the first marker, and was always going to be too artful to let him by after that. Following the turbulence of midweek, on and off the water, this proved more akin to chess on an invisible checkerboard of gusts, the bay merely sliding and sighing below. It might have suited the crowd, sprawled upon a sunny hill, but the less exposed course made for a nuanced, stressful business. At the end Ainslie pumped his fists, unfurled a Union flag – and, as though incarnating his relief, lit two ochre flares.

"That was the most nerve-racking experience of my life," he confessed. "Conditions were so variable that it was impossible to keep tabs on two guys at once. But I've been doing this for a long time, been through a lot of scrapes in my career."

However uncongenial the challenge, the milieu could scarcely have been better for his Olympic swansong: beyond lay the cliffs of Purbeck, guarding the kingdom even as they dozed in the sun; above, rags of idle cloud.

"When I started sailing, as an eight-year-old in Cornwall, in duffle coat and wellies, I never imagined I might be standing here all these years later," Ainslie said.

"It was a really tough week. Expectations were so high, and Jonas sailed one of the best series I've ever seen. But this was the time to do it, in front of a home crowd. For all the people who have supported me – over the years, and here today – listening to a crowd like that makes a difference. After six races I was in trouble, but I turned it around and got it right when it counts. I don't want to go through anything like that again in my life."

It seems unlikely that he will be doing so in Rio in four years' time. "You never say never," he said. "But it's all but impossible to expect anything as good as this. I'd need a very good reason to come back. Slowly, things start to fall apart, physically. You're pushing yourself to the limit, and your body doesn't always like it."

He expressed a due debt to his physiotherapists and above all to his coach, "Sid" Howlett. In essence, however, all these golds – which, along with a silver in Atlanta, take Ainslie past the great Dane Paul Elvstrom – have been forged in an untouchable blaze of desire and mental strength. When it was over, he shook hands with Hogh-Christensen, even helped him haul his dinghy up the slipway. But Elvstrom's vanquished compatriot knew he had been scalded by some strange, implacable force.

"No doubt," said Hogh-Christensen. "Ben is the best sailor of modern times. I was able to give him a run for his money. Maybe it would have been fun to have a bit more breeze. But you can't control the weather."

Looking across at Ainslie, he cannot have been so sure. As Slater said: "Ben turns it on every time. Just keeps a cool head, takes minimal risk for maximum gain. Without a shadow of doubt, he's the greatest sailor in the world."

Ruling the waves: Ainslie moves up

* Most decorated British Olympians

Chris Hoy (Track cycling; 2000-12) 5 golds, 1 silver, 0 bronze: 6 medals

Steve Redgrave (Rowing; 1984-2000) 5 golds, 0 silver, 1 bronze: 6 medals

Bradley Wiggins (Cycling; 2000-12) 4 golds, 1 silver, 2 bronze: 7 medals

Ben Ainslie (Sailing; 1996-2012) 4 golds, 1 silver, 0 bronze: 5 medals

* Sports Personality of the Year odds

8-15 Wiggins

3-1 Jessica Ennis

6-1 Andy Murray

18-1 Mo Farah

40-1 Hoy

50-1 Ainslie