Sir Ranulph Fiennes on his secret world-record attempt and most gruelling expedition

Did you grow up wanting to be an explorer?

Until I was 24, I wanted to do what my Dad had done, which was to command the Royal Scots Greys regiment. He was killed in the war as the commanding officer and that's what I wanted to do. And it was only because of my inability to get A Levels and therefore I couldn't go to Sandhurst, I was forced to make a living out of expeditions. That's what I'd been doing in the army and the only thing I could do.

Out of all those expeditions, which was the most gruelling?

Probably the most physically and mentally gruelling was one with Dr Michael Stroud in the early 90s. We were attempting to break a world record: to be the first people to cross the Antarctic continent unsupported. That is not the same thing as Antarctica. If you can imagine a dirty great birthday cake with wet icing on top, the cake is the continent, where the icing or floating ice spills over the edge and stretches out into the sea for up to 500 miles is Antarctica. The continent is the land mass and always stays the same.

Why was it especially difficult?

We towed greater loads than any previous expedition, thereby having enough food to do 16 nautical miles a day for 97 days. And we never – due to a blizzard or diarrhoea or an accident – failed to do 16 nautical miles on a single day because you'd never do 32 the next day and you'd then run out of food. So you end up towing 485 pounds on day one, which is considerably more than Scott or Shackleton or any previous human expedition, which is why it hadn't been done even by the Norwegians. We actually had to do an extra 400 miles as well to get started from where the ski plane dropped us off.

So you'd have to carry on in the event of a blizzard?

You have to. There was no GPS and no satellite phone in those days. You are using two watches: one on Greenwich time and the other on local time. Using the time on your local watch, you look at the position of the sun and use the sun and your body shadow. So on your way to the South Pole, the sun will be Due North at midday, therefore you tread on your shadow at midday and you know you're heading for the South Pole.

https://www.youtube.com/watch?v=4G9IiA4OWko

What was the key to success?

Planning the rations. Michael Stroud is a senior lecturer in nutrition at Southampton University and he specialises in stress nutrition and the effects of starvation. So he was the perfect person to plan a thing which depended on controlled starvation. I set out at about 15 and a half stone and by the halfway point, which is the South Pole, I was down to under 10 stone, despite eating 5000 calories a day.

What were you eating?

Fat. You need maximum calories for minimum weight and fat gives you many more calories for less weight than protein or carbohydrate. In the UK, if somebody has more than 20% fat in their daily food, they will become obese. We ate 59% fat for 97 days, which is not good for your cardiac system.

What went through your mind out there?

Well, you try desperately not to think of the endless, endless snow ahead of you. 1400 miles of it. Very, very many times you think: Why am I doing this? You're trying desperately not to think of the gangrene and crotch rot. On one occasion Mike plunged a needle into the sole of his foot with no anaesthetic to get rid of a whole load of pus.

So the spectacular scenery was a welcome distraction?

You want it to be white without being spectacular, because spectacular means mountains coming through the snow. It means dirty great crevasses disturbing the snow into which you might fall.

Were there any upsides?

Winning the world record before the Norwegians do. We don't mind if people do it again because we were first.

What's the next world record attempt?

Well, there's this thing that I can't talk about until mid-July because we're frightened of accelerating the efforts of our rivals. If it's successful, it will raise £3 million for Marie Curie. If it's not successful, it will probably raise 10k. Unfortunately there are five other people who could do it first: a South African, three Norwegians and an American.

Do you think you'll ever retire?

I hope not. Not while the Norwegians are still trying to do things. They're the best. I don't know why but they are unfortunately extremely able.

Born on the Same Day is on Tuesday 14th June on C4 at 9pm.

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