It is an achievement that brought tears of joy from his younger sister and pride for the whole family.

Craig Richardson, the 25-year-old former RAF Regiment senior aircraftman from Dereham, never dreamt he would be able to run a marathon when he lost half his leg in an explosion in Afghanistan in 2008.

But as time went by his resolve strengthened, and on Sunday he did just that – Craig completed the 26.2-mile course in London, along with tens of thousands of other runners, with a time of just under five hours, 46 minutes.

Recuperating two days after the race, Craig said: 'I'm proud of myself to have finished it: I always said I would.

'I'm a little bit tender but I was expecting to be sore. I didn't think I'd be able to walk as well as I am now: stairs are a little bit of a challenge.'

He added: 'I feel about 90 years old today!'

Craig, wearing his special carbon-fibre blade tailor made for running, was taking part for the Norwich City Community Sports Foundation (CSF) team effort and by yesterday had raised �2,500. Money from the CSF helps to finance disability programmes for disadvantaged and disabled youngsters in Norfolk.

On London Marathon day Craig's mother, Ann Freeman, brother Jamie Freeman, 16, and sister Paige Freeman, 14, all from Dereham, provided vital moral support around the route.

Mrs Freeman said: 'We were blowing horns and just went mental when we saw him! We were screaming and jumping up and down. I think Craig heard us before he saw us. We were all very emotional.

'I'm really proud of him. The only thing that worries me now is what he is going to put me through next.'

Jamie, a student at Northgate High School, said watching Craig run has inspired him to take part in the London Marathon.

Also among his family was Paul Sandford, landlord of the Railway Tavern in Dereham and owner of Joint Effort gym at Wells, where Craig did some of his training. He also organised the minibus to take them to London.

The former serviceman, who was medically discharged from the RAF in October 2011, thanked his friends and family for their support and said he was keen to raise more money for the CSF or other disability charities in the future.

He said friends have suggested he should do a charity row across the English Channel or a bike ride and added that he would consider competing in the New York Marathon.

'Everyone can do the marathon if they put their mind to it - you just have to dig deep. I wanted to prove to myself that I can do things that I could do before the accident,' Craig added.

He started the 26.2 mile course from the green start, along with 3,000 other competitors, and said everything was 'plain sailing' until the 12 mile mark when he started experiencing pain in his Achilles tendon and the stump of his right leg.

Craig first spotted his family at the 11 mile mark, just before Tower Bridge, for the second time at 18 miles in Canary Wharf and finally at 24 miles near Big Ben.

He said: 'It was amazing. Everyone was cheering me on and giving me encouragement. The atmosphere was electric. People were patting me on the shoulder and shaking my hand and when they saw my leg they said I was an inspiration.'

Despite the pain, Craig added his family support provided a real boost and amazingly found the energy to keep running during the final few miles.

'It was heaven when I knew I was on the home straight,' he added.

Craig is currently in his first year of a University of East Anglia two year foundation degree in Sport, Health and Exercise, at City College, Norwich.

He plans to complete a third year in the same subject, which will give him a degree qualification, and would like to work with disabled people as well as continuing to volunteer for the CSF.

Other people who completed this year's London Marathon included:

-Fakenham runner Colin Stark, a member of the North Norfolk Beach Runners, completed the London Marathon in two hours 57 minutes.

-Emma Potter-Campbell who completed her first marathon for Help for Heroes in three hours 52 minutes.

-Ian Odgers, from Dereham, ran the marathon for Cancer Research UK in memory of his grandfather.

-Nic Sheldrake, from Great Dunham, ran the London Marathon in five hours two minutes. Including sponsorship for the race, he has raised just under �5,000 for the Brittle Bone Society. Mr Sheldrake's wife, Julie, and son, Thomas, both have a brittle bone condition.