Leeds University graduate Mr Cool, aged 34, has been climbing for 14 years. During that time, he has scaled Everest five times and also clocked up an impressive number of firsts, including being the first person to conquer the Arwa Spire in the Indian Himalaya and the south-west ridge of Annapurna III.

It was Mr Cool who trained Sir Ranulph, who suffers from vertigo and is an admitted beginner when it comes to climbing, to the point where he was able to successfully climb the icy north face of the Eiger.

So, although he was initially unsure about taking on the challenge, he knew he was the right person to lead Sir Ran – whom he describes as his "childhood hero" –- in his second assault on Everest.

He said: "It's a massive thing to take on board. He's 64, he's had his heart bypass and everything else.

"It was a whole week before I said yes. But, with Sir Ran, I knew he was going to do it regardless – that's what sort of person he is.

"If he went up with somebody else and ran into difficulties I'd feel pretty responsible.

"I thought, I've got one of the best records on Everest and if anybody can get him up and down safely I think I should be part of that team."

Mr Cool was born in London and studied geology at Leeds University, where his inclinations towards hockey were replaced by a love of the mountains.

After graduating, he trained to be a mountain guide and now lives in Chamonix, in the French Alps, where he spends his days leading people up and down the peaks – as well as finding the time to complete his own challenges.

He said: "I was really lucky to be at Leeds University when there was so much energy in the climbing club that you couldn't help but to get caught up in it.

"The proximity to the Dales was fantastic and, out of our group, five of us are now qualified guides.

"I came to Leeds as a hockey player and left as a dedicated climber, but it wasn't until 2003 that I started training as a guide.

"Training takes up about four years and, when you come out at the end, you're skilled in everything across the board and internationally recognised.

"It's a pretty full-on qualification that takes up a lot of time and dedication. You have to give up a lot of things to get through the scheme – I gave up a few girlfriends because of the sheer amount of time you have to spend away from home.

"So it was hard work, but very fulfiling. I love what I'm doing now, working out here is fantastic."

Mr Cool's relationship with Sir Ran goes back to 2005, when the pair met while Sir Ran was in training in the Swiss Alps to prepare for his first attempt on Everest.

He said: "I wasn't climbing with him at that time but we shared one or two evenings together. He was a childhood hero of mine, so I made a beeline for him.

"When he came out to the Alps about six months later to visit a mutual friend of ours we went out for dinner and he said the north face of the Eiger held aspirations for him.

"He asked if I'd be prepared to train him up to climb it and that let to our wonderful ascent of the north face of the Eiger. After that, Sir Ran vowed he would never climb again. I thought that was sad, but one of those things."

Sir Ran's decision to keep away from high altitudes didn't last long, however. And when he made up his mind to have a second crack at the world's highest peak, Mr Cool was his first port of call. The trip is funded by Yorkshire millionaire Paul Sykes.

He explained: "I got taken to one side by Sir Ran and Paul Sykes and they said Sir Ran was thinking of going back to Everest.

"They asked, would I be willing to take him on board and get him up and down safely.

"I wasn't sure at first, but we'd had such success on the Eiger that it was a no-brainer."

Asked if Sir Ran's cardiac difficulties which forced him to abandon his 2005 Everest attempt were a worry, Mr Cool said that the team had done everything possible to ensure this expedition was a success.

He said: "There's always a number of things that you're worried about. But when Sir Ran had problems in 2005 it was an appalling year in terms of weather. Altitude is very bad for your body, and Sir Ran spent a lot of time above base camp. I think the whole thing just built up.

"On summit day something went wrong, and he made the very wise choice to come back down again, which I completely respect. It wasn't a failure at all. The fact that he came down, with all his fingers and toes intact, was a resounding success.

"This time we've got more oxygen and more Sherpa support. I've climbed with Sir Ran for the last three years and I know what makes him tick.

"You don't climb Everest fast, you just chip away on a daily basis. We go up and go back down to acclimatise, and that should suit Sir Ran down to the ground – but you can never rule out having problems.

Mr Cool explained that, on this trip, the team will be tackling the south side of Everest, the side conquered by Sir Edmund Hillary, rather than the north side which Sir Ran attempted in 2005.

He said: "We'll be spending less time at high altitudes and, if it does go wrong, we can get the person who's ill down very very quickly. It's my fifth year in a row on Everest and I believe I'll keep going back to the south side rather than the north side. I personally think the south side is a safer side of the mountain to work on." Their training includes climbing the Matterhorn to prepare for high altitudes.

Mr Cool said: "Sir Ran is incredibly fit, he goes running for two hours at a time every other day. He's at least as fit as he was when we climbed the Eiger. In fact, he's in tip-top health. It's really good to team up with him again."

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