Ashley McKenzie grins broadly as he tells how a fight over a Pokemon card turned him from a problematic youngster in trouble with the law to one of Britain's best hopes for a judo medal at the London Olympics.

Thrown out of school, his life was changed when he was 11 by a tussle on a street near his home in west London which broke out when another boy tried to make off with his prized Pokemon Charizard card.

'This Charizard was the best card. It was my life back then,' he recalled at the British judo team's training base in Dartford to the east of London.

Pokemon warrior: Ashley McKenzie (front row, second right) with the rest of Team GB's Olympic squad

'I've gone to grab his shirt and next thing I knew I was over his shoulder. I was a scrapper back in the day so I knew this wasn't right.

'I went for him again and as I've gone for him he's thrown me again. I was thinking "No way, what's going on? How's he throwing me? He's hurting me".'

Baffled, he went home and looked on the internet where he discovered he had been overcome by a judo move. Keen to learn more, he went along to a local club and found his erstwhile attacker there, along with his Pokemon card.

'We spoke, we're friends, I started judo. Obviously I got my Pokemon card back,' he added with a laugh.

McKenzie, now a charming 23-year-old, is very open about his past troubles, and proud of how he turned his life around.

Hope: McKenzie is one of Britain's best gold prospects

He was regularly excluded from school and spent time in a young offenders institution.

But, having got into judo, his talent was spotted and success in junior competitions followed.

'I started winning more and more, and I thought my mum's happy and my brother and my dad's happy for me winning these and when I'm in school I'm always in trouble,' he said.

'It was like a balance where I was doing something positive. So I kind of focused all my energy on judo. From there my life kind of shot up.'

It was not all plain sailing as his penchant for trouble has seen him earn a number of bans from the sport. But the medals kept coming and he knuckled down when he realised he could get to the Olympics.

'It sunk in my head, I could actually do this. This actually could be my dream, my dream could come true to be someone in the world,' he said.

He is desperate to win a medal in London in front of his friends and family but knows it will not be easy, especially with Uzbekistan's Rishod Sobirov a huge favourite in his under-60kg category.

'I've come from so low to so high in my life. I've done what I had to do and this is the end spot,' he said.

'I've completed the one big barrier that's getting out of all the trouble, trying to go to the Games. Now the next step is let's try and get a medal.'

If he doesn't succeed this time, then he's even more determined to prove himself at the Olympics in Brazil in 2016.