Sir Ranulph is a big, handsome man, usually. He is related to Ralph Fiennes, in that they share the same great-grandfather, and have similarly very green, still, transfixing eyes. Sir Ranulph, now 55, is incredibly fit. You have to be if, say, you are bonkers enough to want to walk solo across the Antarctic, unsupported by any outside help, pulling a 500lb sledge which is "akin to dragging two 17-stone men in a bath through sand". But today he looks terrible. He has a big, fat scab of a sun blister on his lower lip. And his fingers, I note with mounting horror, are swollen to perhaps triple their usual size, and look much like unpricked sausages in a pan.
"Eghh! Ranulph! Your fingers!" I cry in my manly, strong-stomached way. He explains that he has just returned from the 1998 Eco Challenge Adventure Race which, this year, was held in the Atlas mountains in Morocco. He had to camel-race, mountain-bike, sea-kayak, ride a stallion bareback, climb, canyoneer and do a lot of other things that you will not find included in Fit for Nothing, which highly recommends lying on a sofa and watching daytime telly for satisfyingly long periods. Anyway, he fell off his bike at one point, must have got thorns stuck in his fingers, "and now they seem to be poisoned". Jesus, I say, do you want to carry on? "I'm fine," he says in his wonderfully cold way. Will your fingers get better? "I had a go at them last night with a needle. I got quite a lot of the pus out. If I were in a tent in the Antarctic, I would take a painkiller, then slice into them with a scalpel."
I put my own fingers in my ears, and go: "La, la, la", which, I have found, over the years, works well when you don't want to hear something disgusting. I tell him my fingers are not coming out until I have it in writing that he has finished with scalpels and pus and all that malarkey. I tell him that I am so brave myself that, whenever I go to the dentist, and the nurse tucks a tissue round my neck, I'm already screaming: "It hurts. It hurts. Give me an injection." What's the worst pain you've ever been in, Ranulph? "I'm lucky in that I've never really been in pain," he says.
Never been in pain? What about when, in 1982, somewhere far north of the Arctic Circle, you pulled off your frozen balaclava, and a big lump of beard and skin came with it? What about when, in 1990, during one of your repeated attempts to reach the North Pole with no outside help, your frost-bitten toe turned gangrenous, with part of the rotten flesh coming away in your sock? "These things sound worse than they really were," he says. OK then, why would anyone want to subject themselves to these kinds of things anyway? "It's my living," he says. Oh, come on. You could do something else. You could, presumably, work full time on the after-dinner lecture circuit. "I couldn't. Will Carling has just launched himself on it. Trevor McDonald will do so when he retires. It's a crowded business." Are you planning another expedition? "Yes. But I can't tell you anything about it, because the sponsors are getting cagey."
The thing about Sir Ranulph is that you just cannot get him to say he does what he does because he likes it. And that, like an old boxer, he has to keep returning to the ring for the sensations that tell him he is alive. His expeditions were worth something once. But now that there is nowhere left to map, what is the point of, say, being the first to get to the North Pole without assistance? And where's it going to end? Who can be the first to get there in a kilt, singing "Una Paloma Blanca"? It isn't exploration any more, is it, Ranulph? It's just a mad, reckless, valueless, endurance sport. He won't have it, of course. "If someone is doing it, not giving a damn whether it's been done hundreds of times before, then it's a sport. But if you have someone who is doing it because it's their career, and they specialise in the big ones that haven't been done, for which you need a lot of skill and experience, then it is not."
Sir Ranulph needs to keep going on these lunatic trips, perhaps because the one thing he's never really learned to handle is ordinary life. What, Ranulph, do you enjoy, aside from expeditions and getting fit for them? "Enjoy?" Yes, Ranulph. "My wife runs a farm in Exmoor. I enjoy it there. I like scraping muck." He has no children. He and his wife, Ginnie, tried for 17 years with no success. "We went to lots of clinics but they could never find anything wrong, and then we got beyond a certain age." What a great disappointment, I say. "Oh, there's no point worrying about things you can't alter," he says.
Money is the only thing that seems to engage him, although he seems reluctant ever to spend it. Are you ever extravagant, Ranulph? "Never. Nor is my wife. We don't buy new clothes. We drive a 10-year-old car which, when I crash it or scratch it or whatever, I don't repair, because it might get crashed again in the same place, and so it would be a real waste of cash."
Sir Ranulph, certainly, is not of the school that feels outer journeys somehow represent inner journeys. Indeed, he deflects any attempts to probe for deep motivation, and even takes pride in the fact that when he took part in the radio programme In the Psychiatrist's Chair, Anthony Clare described his efforts to uncover his inner being as "being like stirring a void with a teaspoon". I would say, however, that it's not so much a void in there; more something that he fears to look at too closely, because whatever is revealed might not be especially pleasant. So not a brave man on all counts, no.
Sir Ranulph Twisleton-Wykeham-Fiennes is descended from the Emperor Charlemagne. By the time Ranulph was born, in 1943, there was a title but no money. His father, a colonel of the Royal Scots Greys, was wounded four times in North Africa and was awarded the DSO before dying in a battle near Montecassino, four months before Ranulph's birth. Ranulph already had three older sisters, "so the fact I was a boy must have been some consolation for my mother, yes". His unknown father was always his hero. "From childhood, I wanted to be as he was." Perhaps he also wanted to do as he did, and become his substitute. Perhaps this is why he became an explorer. The dangers, the fact you could drop down an ice crevice at any time, is as close as you're going to get to living with death in peacetime. Sir Ranulph won't accept this either, of course.
He was brought up in South Africa, where he was surrounded by women: his grandmother, mother, three sisters, the maid and the cook. Certainly, it sounds as if he felt compelled to assert his masculinity. "My mother had to use a cane because I was very bad." Bad in what way? "I remember, once, coming into the kitchen and seeing this gorgeous chocolate cake. I said to Mary, our black cook: "Can I have the chocolate cake?" She said: "I've been told you can't have the chocolate cake." I knew where my mother kept her Browning pistol. So I went upstairs, got it, came back down with it, cocked it at Mary and said: "Mary, the chocolate cake." He got a terrible caning for that, but got his own back by scratching his mother's stockings, "which, it being just after the war, were hard things to come by". Something not very pleasant in there.
He went to school in South Africa until he was 11, and the family returned to this country, to Sussex, so Ranulph could attend prep school here, then Eton. He had a tough first three years at Eton. Being exceptionally pretty, he was dubbed "tart", his bottom was pinched, he was blown kisses and wolf-whistled at. For someone whose masculinity had become such an important thing, this was excruciating, and he even contemplated suicide by throwing himself in the Thames. But he decided to survive, by boxing, at which he excelled, and climbing the school buildings at night. "I sat atop the dome, high above the roofs of Eton, and felt infinitely superior to every one of the boys in their cosy beds below."
He is quite an egoist. He wanted to go to Sandhurst, so he could become a colonel in the Scots Greys like his father, but couldn't go because, even though he'd been dispatched to a crammer, he failed his A-levels. Possibly, he wasn't bright enough? He says: "It was the time of Mary Quaint [sic], and I was distracted by Norwegian girls in miniskirts."
He joined the Army, and made it to the SAS, where he got up to no good. He stole gelignite and detonators and tried to destroy the film set of Doctor Doolittle in Castle Combe ("they were ruining the countryside"), for which he was sacked from the regiment but escaped a prison sentence. He then volunteered for the Sultan of Oman's army to fight the communists. He returned to this country in 1970, and married his childhood sweetheart, Virginia Pepper, whom he met when he was 12 and she was nine, and they were neighbours in Sussex. I wonder how she has coped with her childlessness. He says: "Her maternal instinct has gone into looking after her cows. She knows every one by name." Are you romantic? "Romantic?" Yes. "My wife would say, quite longingly, that I'm not." Where did you propose to her? "In a Mini in the back street of Midhurst during shopping hours."
He also made his first expedition in 1970, surveying a Norwegian glacier and, a year later, canoed across British Columbia. His longest and most famous expedition, the Trans Globe, took place between 1979 and 1982, and after he and his companion, Charlie Burton, became the first people to reach both North and South Poles overland. But between 1986 and 1996 came six unsuccessful attempts to reach the North Pole without help from outside. I say, have you ever heard the Japanese saying that translates as: "There are two kinds of fools. Those who never climb Mount Everest and those who do it twice"? He says this doesn't apply. "I don't think I have ever done the same thing twice. All my expeditions have been quite different."
So, yes, Sir Ranulph will continue to be "the world's greatest living explorer", even though there isn't really anything left to explore. Possibly, he needs the Antarctic a great deal more than it needs him. Anyway, he's got an appointment with a doctor to have his fingers drained. I shake his poisoned hand. He, of course, doesn't even wince. He just says: "Independent readers are good hardback buyers. Aren't they?"
`Fit for Life' is published by Little Brown at pounds 16.99. `Fit for Nothing' is by mail order only - let's face it, if you want it you're not going to miss `This Morning' to go down the shops for it