The 35-year-old (pictured) from Havering in Essex, who retired from competitive swimming in 2007, had bone cancer twice when he was a teenager and his treatment, which included chemotherapy, radiotherapy and numerous operations, lasted for two years.

He managed to triumph in his battle to successfully overcome the cancer that threatened his career to become one of Britain's most successful Paralympic swimmers with a total of 20 major championship medals.

But he admits that he has never forgotten the support given to him by TCT in his battle with cancer and says that he wants to give something back to the charity.

"I had bone cancer twice when I was a teenager," explained Long.

"The first time round the NHS viewed patients as either a child [under 12-years-old] or an adult.

"Consequently I was treated on a geriatric ward.

"It was a nightmare when the cancer returned but by then the first TCT ward had opened and the difference was incredible.

"Everyone looked happy for a start - I honestly couldn't believe that people on this ward were being treated for the same thing I'd had just 18 months before.

"The TCT make a huge difference in many ways but perhaps most surprising is that patients that go through their wards are nearly 20 per cent more likely to survive.

"So I've decided to run for them."

Long, who was awarded an MBE in 2005, now works as a motivational speaker and a television presenter.

He will play a key role in the Channel 4 coverage of the London 2012 Paralympic Games, where he will work as one of the on-location reporters.

Long aims to raise £2,000 ($3,200/€2,400) by running the 26 mile course around the capital.

"Any support you can give is massively appreciated," he added.

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