"I said I didn`t think this was something I wanted to get involved with. I want to play football and I`m going to school so I don`t want to do that," he says.
So he travelled to neighbouring Guinea where he met a French man, who pretended to be his friend and promised to help him fulfil his dream.
"I didn`t know he had another different intention - to get me into the sex trade," Bangura explains. The pair travelled to France and on to the UK. Once there, the man left him alone in a building.
"All of a sudden I saw two or three guys come around me, trying to rape me and make me do stuff," he says.
"Because I was young and I was small, I just started screaming. They probably thought I knew what I was there for - obviously I know what I came over here for, I was here to play football.
`Crying and screaming`
"I was just crying and proper screaming and I tried to make my way out - I was cold, I was crying, I was shaking, I didn`t know what to do, I was all over the place.
"I made my way outside. I didn`t know where to start, I thought it was the end of my life."
He requested help from a Nigerian man, who told him to go to the Home Office and claim asylum. Because he was 16, he was later given a two-year right to stay.
"It was so emotional, because after a few months I`d kind of forgotten about what what I`d been through, it had been sad but I ended up coming to a good thing.
"I started meeting people, started playing football and I got the opportunity to join Watford when I was 16 and things just started building up for me," he explains.
"It`s quite emotional to talk about it now, I`m happy I`ve got over it, but it`s sad for me."
It is estimated that 15,000 teenage footballers are moved out of 10 West African countries every year - many of them under-age.
The figures come from non-governmental organisation Foot Solidaire, which helps send boys back to Africa after they have been tricked by unscrupulous agents into leaving the continent.
The National Crime Agency says its most recent figures from 2014 show a total of 2,340 potential victims of trafficking were referred from 96 countries - of these 29% were minors.
But Independent Anti-Slavery Commissioner Kevin Hyland said he believed more children were trafficked to the UK than the official figures suggest.
Sports journalist Ed Hawkins has just spent two years investigating the football trade for a book called the Lost Boys.
"It`s difficult to put a number on it, but it`s probably in the thousands each year. People aren`t aware of the scams, how the culture of greed permeates from top to bottom (in football) and encourages the slave trade," he says.
`Window dressing`
A Fifa rule called Article 19 says clubs cannot sign people aged under 18, but it has caveats.
"It`s not worth the paper it`s written on, it`s just for window dressing by Fifa, they have given get out clause for clubs to do what they like," he says.
"There should be a blanket ban on the signing of minors - it shouldn`t be allowed at all, Uefa says this should be in place, with no caveats at all. That would help reduce the numbers."
Bangura, who also now works with charities to publicise the issue, said: "I think there`s loads of vulnerable kids in Africa who want to achieve what I`ve achieved in my life.
"There`s loads of kids who might not even tell their parents, or their parents might use their last money to make sure they come over here to play football and they end up doing something else.
"It`s important for me, having been through what I`ve been through in my life, for me to say I`ve been through that, I`ve survived, but what about the young kids coming up, will they survive, are they going to be able to cope with that, so we really need to find a way to stop all of that."
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