When Guy Disney reaches the South Pole in around a fortnight's time, his journey will have been even more challenging than most. He will have overcome not only temperatures dropping to -49F (-45C), gale-force winds and the very real danger of falling into crevasses and suffering frostbite; he will also have completed the journey on one leg - having lost his limb below his right knee in Afghanistan four years ago.
"I just want to crack on and get started," Captain Disney, an officer in the Light Dragoons, told The Sunday Telegraph from Antarctica on the eve of the trek. As part of a team of four wounded servicemen and women, Captain Disney's British team will race teams from the US and the Commonwealth - with Prince Harry as the patron of "Team Glenfiddich".
"I feel good about the race at the moment. I'm sure we'll have mishaps, but we'll adapt to anything that hits us, and just get on with it," said Captain Disney, who first met the Prince in 2011 on a trek to the North Pole. "I'd say Harry is a dynamo within the team, and he's been a laugh. He brings a huge skill set to the party - and we're very lucky to have him on board."
Today - weather permitting - Captain Disney and the other team members will leave the relative shelter of the airbase on the edge of the Antarctic plateau and begin the arduous 16-day, 205-mile trek. Alongside him will be three other wounded servicemen and women: Kate Philp 35, who in November 2008 became the first British woman to lose a limb in combat; Duncan Slater, 34, aiming to become the first double amputee to make the journey, and Ibrar Ali, 36, who lost his arm while serving with the Yorkshire Regiment in Afghanistan.
It is a world way from the Cotswold village where Captain Disney grew up. The son of John Disney, a GP who also worked at Cheltenham racecourse, and his wife Fiona, a former nurse, Captain Disney, a talented amateur jockey, went straight to Sandhurst to train as an Army officer after graduating from Cirencester agricultural college in 2006.
He moved quickly onto training for operations in Afghanistan, and was deployed in April 2009 to a forward operating base in southern Helmand - one of the most dangerous areas for British troops. "The first few months were spent doing long-range desert patrols in the south-western desert with an ever-rising temperature; the hottest we managed to record in the vehicles was 57C (135F)."
By the end of May his unit had moved to a new area of operations for the big push of the summer in preparation for operation Panchai Palang or Panthers Claw. It was then he suffered the injury. The operation started well, then they pushed through to Babaji, a Taliban stronghold. "We came under fire from a concealed ambush point with a rocket-propelled grenade which pierced the side of my vehicle.
Molten metal went through my right leg and fatally wounded a soldier to my right." Other soldiers recall hearing the emergency call over the radio, made by Captain Disney, in which he calmly said: "I need a heli(copter). I think I have lost my leg." Captain Disney was taken to Camp Bastion for immediate surgery and then on to Selly Oak in Birmingham for further treatment. Three months later he was out of hospital and back on a racehorse soon after.
Three years later, in 2012, he was serving in Afghanistan, taking a more office-based role. Early this year he was selected for the South Pole trek. "There's something that continues to draw me back to this charity and these people time and again," said Prince Harry, an ambassador for the charity, who also participated in the training. "It's toughness of mind. An unquenchable spirit that simply refuses to say 'I am beaten'. In a way, it's something that can't be defined.
You've either got it or you haven't." The Sunday Telegraph joined Captain Disney and his team in Iceland in March, learning how to ski while towing sledges - known as pulks - that weigh 130lbs. Captain Disney, who participated in the 2011 Walking With The Wounded trek to the North Pole, was a comparative expert. Then came 24-hour sessions in the "cold chamber" - a giant freezer in Nuneaton where they would ski on machines for two hours at a time, with 10-minute rest breaks, in all their thermal clothes to replicate the Antarctic conditions.
They also had to train extensively at home, with Captain Disney hauling car tyres across the fields near his home. Diet was crucial, with teams stocking up to ensure they were in top condition for the trek. During the race they will consume 6,000 calories a day in "boil in the bag" rations. "The final weeks of prep have been good," said Captain Disney, who flew out to Cape Town amid a rousing send off from Trafalgar Square last month.
"We've had a few upsets, a few vehicle problems, but I think were nearly there. "We're just changing camp at the moment and we're just on the edge of a ginormous ice field which myself, Harry and Iby [Ali] and Conrad [Dickinson] the guide went and checked out yesterday - and it's fairly difficult stuff."
The teams were held up by bad weather and unable to fly out of Novolazarevskaya, or Novo, airbase - the world's most southerly - when planned. "In terms of getting stuck in Novo, it was a bit of a pain," he said. "But it gave us time to sort out our kit and equipment and now I think we're ready to go. It's minus 30 (-22F) today but the wind has just dropped, so to be honest it's not that bad.
We've just got to be fairly savvy with clothing. We were doing a ski yesterday and that was fairly good; but actually skiing into the wind, away from the sun, that's when you really notice the temperature drop." The Britons are keen to begin the race against their rivals from the Commonwealth, led by Dominic West, the old Etonian British actor, and the US, with the Swedish actor Alexander Skarsgard.
"We are competitive. We're racing against a man who's blind - but he'd probably beat us there in days. We want to get there first, but if we do we'll be very glad when everyone else gets there as well." The risks are ever present - amputees' stumps need extra special attention, with their limited circulation, in freezing temperatures.
But Captain Disney shrugged off the danger, joking that the scariest moment so far had been a flight to the start point on a light aircraft that was built in 1943 and flew over Arnhem. "So the flight when we got up here to Novo was fairly exciting, to say the least," he said.
"When you take it to a high altitude in cold climate, and try to land in pretty deep snow, that makes it all the more exciting. "The hardest thing so far is seeing your other team-mates suffer. We're at quite an altitude here, and then gearing up for the race does create an element of tension with the other teams.
"And also not knowing what is going on back home. We're all wanting to be doing this, but if it's all for a donation of about a quid then I think people would be pretty annoyed to be honest. We're very much hoping people are donating."
Donations to Walking With The Wounded can be made via their website - www.walkingwiththewounded.org.uk - or by texting "WWTW01 pounds 10" to 70070 to donate pounds 10.