How are you going to top that, Ranulph?

Now he has reached the top of Everest – at the third attempt – the world's greatest living explorer is running out of new challenges

Exhausted and fearful for his health, Sir Ranulph Fiennes turned his back on the summit of the world's highest mountain for a second time a year ago and declared: "I won't try Everest again. The first time I got a heart attack. This time, bad timing and weather scuppered my chances. I think any third attempt would be bad luck."

Never one to be restricted by such trifles as fate or his own wellbeing, the 65-year-old explorer and survivor of heart bypass surgery yesterday set aside his vow and trudged through the darkness to finally stand on top of the world.

In so doing, he became the first British pensioner to climb Everest and the first human to have crossed the globe via both poles and climbed its highest peak. After reaching the 8,848-metre summit about 1am British time, he said: "This is the closest you can get to the moon by walking. It's amazing where you can get with a bus pass these days."

Sir Ranulph's arrive on Everest's peak took place with less fanfare than his two previous assaults in 2005 and 2008, which were captured by an entourage of television cameras. This time, he was accompanied by a lone BBC crew which was only allowed to reveal the attempt once it had reached its conclusion.

But the triumphal end to the low-key climb was no less poignant for Sir Ranulph, who had returned to the mountain to finish raising £3m for a cancer care charity, following the loss of two sisters and his first wife, Ginny, to the disease.

The explorer said he felt "dreadful but pleased ... I have summited Everest for Marie Curie Cancer Care, which has long been a personal goal".

Sir Ranulph has led more than 30 expeditions to the most inaccessible and cruelly testing environments on the planet. The Old Etonian and former SAS demolition specialist is best known for his three-year circumnavigation of the globe via both polar ice caps, completed in 1982, as well as his attempts to walk to the North and South poles alone and unsupported.

During his unsuccessful attempt to reach the North Pole, the explorer suffered extreme frostbite to his hand after he plunged it into freezing water to retrieve a sledge.

Unable to bear the pain from his blackened fingers while awaiting surgery back home, he removed the damaged bone and tissue in his garden shed using a vice and an electric jigsaw.

Four months after undergoing triple heart bypass surgery in 2003, Sir Ranulph achieved another feat of endurance by running seven marathons in seven days on seven continents. He is listed in the Guinness Book of Records as the greatest living adventurer.

Not withstanding a morbid fear of heights, Sir Ranulph could be forgiven for believing that luck was against him after setting his sights on Everest. His first attempt four years ago was abandoned at 8,500m when he suffered a mild heart attack. He turned back from his second assault last year at 8,400m due to a combination of bad weather and exhaustion, but still managed to raise £2.6m for Marie Curie nurses. He decided to return to raise the remaining £400,000 needed to meet his target.

A spokeswoman for the charity said: "He was very frustrated that he didn't succeed last time... this time he didn't want to be distracted by making it high profile. It was kept low key so he could concentrate on the climbing."

Before his assault on the summit, Sir Ranulph said he had a new formula to conquer his bête noire: "Forget about thinking that you are going to succeed. You have to just keep plodding. Imagine it is a mountain with no top."

His third climb was defined by good fortune. Kenton Cool, who has climbed Everest six times and accompanied Sir Ranulph, said they encountered some of the best weather conditions he had seen on the mountain.

After spending three weeks acclimatising at base camp, the two men set off for the final stage of the climb on Wednesday, to walk through the night in oxygen levels a third of those at sea level. Sir Ranulph, who arrived at the peak shortly after a group of Indian soldiers and planted a Marie Curie flag, told the BBC: "We came to the summit as dawn broke. It was very, very cold."

Despite his recently acquired bus pass, the explorer made it clear that he has no plans to hang up his crampons. As well as writing his 19th book at base camp, he also spent time planning his next, as yet unannounced, expedition.