Never backing down: why Sir Ranulph must conquer Everest

Will it be harder to say goodbye this time? At first, Sir Ranulph Fiennes doesn't understand the question. He left his childhood sweetheart Ginny many times during the 35 years they were together as explorer and wife, until cancer made her the one who left. He will say goodbye to his second wife Louise on Wednesday, when he sets off for a second attempt at climbing Everest, the mountain that once nearly killed him. "Both wives knew what I did for a living," he says. "If they had wanted to marry someone who stayed at home, they could have done so."

Louise fears he will die. The last time he tried to climb the world's highest mountain, Sir Ran suffered a heart attack 300 metres from the summit and was only saved by his sherpa guide. His wife thinks he is too ill to try again. But that's tough. "I disagree with her."

Not even the Chinese government can stop him trying: it has closed the mountain, in order to take the Olympic torch to the top undisturbed by protests, but the Fiennes party is going to Nepal this week anyway. They hope restrictions will be lifted before the short climbing season ends. Sir Ran became a soldier as a young man "to fight communists", so he's not about to surrender to the Red Army now.

But while officialdom is there to be defeated, and wives have made their own (lonely) beds to lie in, daughters are different. For the first time in his life, Sir Ran has someone else to think about: Elizabeth, born two years ago when he was 62. Fatherhood has made other adventurers stop and face the challenge of staying at home, so what about him? Won't it be harder to go this time?

"I can see why most parents would think it is more difficult," he says, as we sit in a near-empty restaurant high above London, in the old NatWest tower. There is a coldness in the things he is about to say, which might be shocking if you heard them from any other father, but seems natural in a man who has made his name suppressing emotions while traversing ice and snow. A man so out of touch with feelings such as fear that when he got frustrated with the way doctors were treating his frostbitten fingers, he just locked his hand in a vice at home and hacked off the dead digits with a fretsaw.

"I suppose everybody responds differently, with different emotions, according to their past," he says. What does that mean? "I was born with no father ... but with a lovely mother. My daughter has got a lovely mother. Louise is an incredibly good mum."

He doesn't look like the World's Greatest Living Explorer (to quote Guinness World Records) when he says this. He looks like somebody's slender grandfather, dressed in khaki chinos and a dark blue double-breasted blazer with brass buttons. His greying hair is swept back from a balding head. But that bulbous nose is not the result of too much claret. It is frostbite, got a week ago while climbing in sub-zero temperatures in Italy. The fingers on his left hand stop at the knuckles. And the desert boots on his feet are not split along the sides because they are old, but to relieve feet that complain after crossing both the north and south polar ice caps, running seven marathons on seven continents and the many other extraordinary – some would say crazy – things he has done in life as a professional adventurer.

The implication is that he would not expect to be missed by his daughter. "I have never missed not having a dad. Ever." But is that true? Many people have tried to work out what drives Fiennes – Professor Anthony Clare said trying to fathom his personality was like "stirring a void with a teaspoon" – but talking about his father like this, which he does rarely, gives a very big clue.

He has already brushed off any idea that the original conqueror of Everest, Sir Edmund Hillary – who will receive the rare honour of a memorial service at Windsor Chapel on Wednesday – was his boyhood hero. Now, he says: "If you ask who my hero is, my hero has always been my dad. Because of what my mum told me about him. He was killed in the war, commanding a regiment. He was wounded five times and so on."

Lieutenant Colonel Sir Ranulph Twistleton-Wykeham-Fiennes (the full name he shared with his son) of the Royal Scots Greys was killed when he stepped on a landmine near Monte Cassino in Italy in late 1943. The younger Ranulph was born four months later, in March 1944, becoming the third baronet at birth. After Eton he joined the Army. "All I wanted to do was to command the same regiment as him," he says. "I spent until I was 24 trying to do that."

The trouble was that he had no A levels, despite the expensive education. "In his day, there was no such thing ... but it meant I couldn't be a regular officer. I couldn't do the thing I had always wanted to do."

Many of his generation felt inadequate compared with the wartime heroism of their parents. Fiennes went looking for a just fight. "I joined the Army in order to fight communists. I fought communists. Some of my soldiers were killed. I definitely would have died for the cause. I spent three years in Oman at a critical time, when the Marxists were about to take over the whole country."

Presumably, then, he has a view on China and its suppression of Tibet? "Yes," he says, "I have got a definite view about China." He is, after all, a member of the right-wing Freedom Association. But every great explorer knows you sometimes have to cut your losses – particularly if you don't want to lose your climbing permit. "Now is not the time to come out with it."

You don't have to be Anthony Clare to guess that record-breaking feats of endurance might be a way of trying to live up to the idealised father. So what would his dad make of what he has become? "Oh I don't know. That's hypothetical."

Hypotheses are dangerous, he says, except when they help with planning. "My attitude to climbing is that we're taking every possible safeguard, going up with the best possible person and with a doctor as well, who has a defibrillator with him." His companions will be Dr Rob Casserley, a medic who has been to the top of Everest four times, and the magnificently named expert climber Kenton Cool, who has the European record for five ascents.

Where do explorers go when there is nowhere on Earth left to explore? They go back. But isn't it a lot easier these days, thanks to modern equipment? His eagle-wing eyebrows flap, as he takes the question as an assault on his entire record. "The journey we did in 1979 to 1982 was three years of permanent travel, 52,000 miles on the surface, and at that point nobody had ever been around Earth on its polar axis by any route," he says. "Nobody has every repeated the journey by any means."

Quite right. The transglobal expedition that made him famous was unique. But listen to him describe what is special about this next Everest climb and you realise how much of a struggle it must be to come up with the new angle for sponsors. "A dozen people have reached both poles and climbed Everest," he says. "But to reach a pole is only half as difficult as to cross an entire icecap via the pole. Only three people have done that across both icecaps. One of them was myself. Assuming that neither of the other two are on Everest right now, I think that I stand a chance of being first."

He will also be the oldest Brit. But the real point is to raise £3m for Marie Curie Cancer Care, whose nurses helped when Ginny was dying. The couple lived on a hill farm on Exmoor, raising cattle and sheep, but this soulmate was so much a part of what he did – acting as base leader on many expeditions – that she won her own Polar Medal. He says he doesn't "do" emotion, but the look in his eyes when he talks about her says something different. He lost Ginny and his two sisters to cancer, all within 18 months.

"Ginny had a strong feeling that I should go and see my sister in America," he says. "I arrived there in the morning and my sister died that night. Unbelievable of Ginny."

Before she died, Ginny was in a hospice. "On her better days we went round in a wheelchair and nattered to the women with no visitors. They were longing to die at home. They had photographs there, and a cat. The only way that could happen was with the help of Marie Curie nurses. They are fantastic. But there aren't enough of them."

That's why he offered, in the days of grief, to do anything he could for the charity. But climbing Everest with a dodgy heart? Isn't that just daft? "It's an unknown factor. It's no good anybody, particularly in my family, saying if you climb Everest you are putting yourself in great danger. Statistically, the people most at risk are salesmen. A wife should be saying: 'Stop being a salesman.' Not: 'Stop climbing mountains.'"

"A wife?" He means Louise, a horse trainer. They met at a lecture he gave soon after the death of Ginny, who had encouraged him to find someone else when she was gone. Louise, 41, has a reputation as a plain speaker. If that is true, she has surely met her match in one of the most wilful men alive.

There have been at least 210 deaths on Everest since 1953. Would he be happy to die up there? "I wouldn't be happy to die anywhere or at any time," he says. "But being a coward, I would prefer to die quickly and painlessly rather than lingering, yeah." As for his daughter, well, she has a good mother. Other than that, she will have to cope with an absent father the world sees as a hero. Just like he did.