Britain's biggest fundraisers

The country's top fund raisers are revealed at the JustGiving Awards 2015

Every year JustGiving - the social-giving platform partners of the Independent on Sunday's Happy List - recognises their top fundraisers.

In a few weeks' time, men, women and children across the country who have made an extraordinary contribution to charity will be crowned the 2015 winners at a glittering event in London.

In the run up to the event, we are telling the remarkable stories of those finalists, who are voted for by the public, across six categories.

Alex Smith, from Surrey, discovered in 2011 with a simple blood test that his son Harrison has Duchenne Muscular Dystrophy. He decided there and then to set up his own charity in his son's name, The Harrison’s Fund, to help find a cure to the illness.

He remembers the day his son was diagnosed as “the worse day of our lives so far”. “It was a shock. You talk about the life you want for your children and then everything was taken away from us and from him. It was a lot like grieving. You are grieving for what he could have been and now they are not going to be that,” he said.

The charity has the purpose of raising as much money as possible to enable the world’s best researchers to halt the illness, or at least slow it down.

Alex has raised more than £48,000 so far by participating in an Ironman triathlon, which included a 3.8km swim, 180km bike ride and a 42.2 km run in just 15 hours, 36 minutes and 29 seconds.

“It’s not only about Harrison, but I hope our children (those with the illness) will be the first generation to survive.”

He didn’t beat a triathlon record but it meant the world to him being able to do it with his son. Alex carried his disabled son, Harrison, the whole way, pulling him in a catamaran behind him as he swam, in a trailer as he cycled and pushing him in a racing chair as he ran.

“I had Harrison with me for 15 and half hours, just me and him. It was amazing to spend the whole day with him. I could hear him (Harrison) supporting me,” said Alex.

Duchenne Muscular Dystrophy is the most common fatal genetic disorder to affect children around the world. Those affected by the illness cannot produce dystrophia, a protein that builds up your muscles, causing the deterioration of every muscle in the body.

Anyone wishing to donate to Alex's fund, can do it on his Just Giving page at: https://www.justgiving.com/GreatestIronMan.

For more information on the Harrison’s Fund charity visit: https://harrisonsfund.com/.