A FORMER firefighter is climbing one of the biggest mountains in the world six years after being struck down with an illness which left him almost powerless for months.

John Robson, from Durham, will be going on the five-week expedition to the Himalayas in October, when he hopes to conquer Annapurna IV, which at 7525 metres is one of the tallest mountains in the world.

For Mr Robson, who founded expedition group Fire and Ice, which has raised more than £140,000 for children's charities since 2004, it will be his biggest peak to date.

"This is the biggest, deadliest, most dangerous compared to what I've done in the past," he said.

"It doesn't attract a lot of climbers so it's going to be us and the mountain. It's very pure."

The expedition comes six years after Mr Robson started having debilitating symptoms including fatigue and rapid weight loss.

Though training for his fifth London marathon, and for an attempt to climb Ama Dablam, another peak in the Nepal Himalayas, he was left barely able to lift his arms or get out of bed.

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After weeks of testing, he was diagnosed with polymyalgia rheumatica (PMR), an autoimmune condition which results in the inflammation of the arteries.

He said: "I couldn't raise my arms for three or four months. I couldn't switch on a light switch. I was in a wheelchair.

"I was told I'd never walk or climb again. People thought it might be cancer or MS, I was being tested for everything. It took five weeks to be diagnosed."

After 21 months of steroids, the father-of-two is now in remission and has been on several smaller expeditions.

He started training for the trip nine months ago.

Mr Robson, who gives inspirational talks about his endeavours, is also the coordinator for support charity PMRGCA North East and is hoping the expedition will help raise awareness about the condition, which primarily affects women over the age of 60.

Now retired as a firefighter, he works part-time at Cotswold Outdoors, in Durham, and also does some teaching at New College Durham.

He said: "For me mountains are a metaphor of life.

"For me PMR was a like a storm in the mountains.

"There are always some storms and there is always some adversity.

"There are opportunities, it's not the end of the world when you get something like that."

He added: "This one will be very emotional. When I get to the summit and look around I will be thinking of all the people who have been supporting me."