When he finished the ordeal, his own mother would have struggled to recognised him.

And Bristol doctor Ed Coats certainly need not fear being mobbed by fans when he walks out his Clifton home.

For most of his trek to the South Pole, the doctor from Southmead Hospital had his face covered by a thick ginger beard and ski goggles.

For 20 days in January, Ed, 28, joined teammates double Olympic gold medallist James Cracknell and television presenter Ben Fogle to race seven other teams to the South Pole.

The doctor, a former international decathlete, is no stranger to physical challenges having swum the English Channel.

The trio finished second in the race behind two hardened explorers from Norway, and from tomorrow viewers of BBC Two will be able to see the trials and tribulations of the race in all its high-definition glory: frostbite, pneumonia, hunger, exhaustion and lots of tears.

On Thin Ice will follow Ed, James and Ben over 12 months of gruelling specialist training, including 36 hours spent in a climate chamber on an RAF base in Wiltshire.

The preparation was intense to give them the best chance in the 450-mile race to the geographic South Pole – where teams ski-pulled 200lb sleds through the most hostile environment on the planet.

Ed, who beat more than 650 applicants from across the UK for a place in the team after actor Johnny Lee Miller was forced to pull out because of filming commitments, has now returned to his job as a doctor of obstetrics and gynaecology at Southmead.

He said the race to the South Pole now seems like a "world away". "It's very hard to describe it and a very hard place to put into words to people who have not spent 20 days in those temperatures with no food and no sleep. If you imagine when you got out of bed it was eight o'clock, you got up and started your day and then looked at your watch when you went to bed at midnight. We would still be skiing and we would have been skiing from the moment you had got up, and we would be skiing for another two hours. We did that day after day."

Ed and Ben both lost two stone during the race, while James, who had pneumonia, lost three-and-a-half stone.

During the race itself, much of the footage in On Thin Ice was shot on small hand-held cameras by Ed, James and Ben, talking about how they were feeling and about difficult moments during the day.

The trio carefully prepared their daily meals before the race began, chopping and cutting high-energy food into small portions. But this all melted into one big mess when they arrived in South Africa for pre-race preparations, and then froze on the flight to Antarctica into a solid block of salami, chocolate and cheese, a vile but calorific snack.

"I used to dream of meals all the time," Ed said. "I worked round lots of restaurants in Bristol, but The Clifton Sausage was my favourite one to think about, I think I got through the whole menu."

For Ed this was a once-in-a-lifetime opportunity and one that he will probably never be able to do again.

"When you step outside your tent, you're standing on the bottom of the world, with nobody for miles around. It's a magical place, so peaceful, very special. Those were some very special moments for me.

"I feel hugely privileged to have gone somewhere as unique as Antarctica. My job is not as an adventurer, I'm a doctor and while I like to keep fit and set myself challenges, I'm sure that I will never have the opportunity again to do something so special, but then, who knows?"

The first episode of On Thin Ice airs on BBC Two on Sunday evening.

See Seven, your 7-day TV guide, free inside today

Ed will be giving a lecture about his race to the South Pole on Thursday, July 2, at 7.30pm at Kingsdown Conference Centre, Southwell Street.

Tickets are £10 in advance, available from Kay Paddock, 0117 928 5470 or email kay.paddock@uhbristol.nhs.uk.

All the money raised is going to The Mothers & Babies Trust in Bristol to fund research into unborn babies.