BOB Wilson originally agreed to join the Headway Oxfordshire charity as treasurer for three years.

But 17 years later, the retired chartered surveyor has cycled from John O’Groats to Land’s End, climbed part of Everest and run three marathons.

He’s raised £25,000 for the charity in the process, but is about to embark on his most daring challenge yet.

To celebrate his retirement as treasurer, the 63-year-old will be setting off to the South Pole on Friday.

He said: “I’m a tad apprehensive. Having watched David Attenborough’s Frozen Planet this week, I can see it’s going to be cold.

“We’re actually expecting temperatures of about -40 C and severe winds of around 20 knots.”

Mr Wilson volunteered for the charity when a friend was seriously injured in a car accident.

Headway Oxfordshire, based in Kennington, offers support to anyone affected by an acquired brain injury, from tumours and strokes to haemorrhages and accidents.

His fundraising efforts began in 1998, when he completed his first London Marathon. Two more followed.

The father-of-two said: “The atmosphere on those runs was just astonishing, it was fantastic.

“I did the first one as I turned 50. But then I had some problems with my legs and the doctor told me I had to stop.”

In 2010, he and two others rode the 1,000 miles from Land’s End to John O’Groats in two weeks, raising more than £6,000. He said: “It was just amazing to cycle through the UK and see how many cultural changes there are through the country.”

In April this year, Mr Wilson, from East Hanney, attempted to climb to the North Col on Everest.

He and two friends made it to 6,700 metres before turning back due to a combination of altitude sickness and lack of time.

He said: “We were just 300 metres short in the end. It’s not a technically difficult climb, but it’s cold and there’s a lack of oxygen. You sit at base camp in your tent and your body is just deteriorating.

“But it was an honour to be there, to be part of the mountain.”

Next week, he will undertake his greatest challenge – skiing 100 miles to the South Pole.

A 10-person team will fly to Chile and then on to Union Glacier, before being flown further into Antarctica.

He said: “I’m under no illusions, it’s going to be hard. But the South Pole is my goal and hopefully I’ll get there.”

Mr Wilson will also spend the 12-day trek learning his lines for his role as the dame in the East Hanney panto this winter.

He said: “I hadn’t realised how much I’d raised until the charity counted it all up. It made me feel quite proud.

“But I just like to keep myself active.”

To sponsor Mr Wilson visit justgiving.com/headwaysouthpole