A reformed criminal has gone from armed robber to youth mentor after turning his life around.

Luke Sewell, 24, of Norbury, was a known character to the police in his teens and was in and out of prison for a host of offences.

But he has now made a complete u-turn and is currently mentoring young people to lead a crime-free lifestyle.

The ex-Riddlesdown School pupil, who used to live in Sanderstead, left school and turned to a life of crime.

He first went to prison as a 17-year-old for five months.

In November 2007, Mr Sewell was sentenced to five years for holding up a shop in South Croydon with a handgun.

After serving two and a half years inside he came out in May 2010.

He returned to prison a few months later after being convicted of grievous bodily harm.

After his experiences in prison, Mr Sewell decided it was time to move away from crime and in 2011, he started volunteering at the Salmon Youth Centre in Bermondsey.

He worked three nights a week from Summer 2011 to the end of the year and after impressing bosses, he was offered a chance to go on the centre’s apprenticeship scheme.

The year-long apprenticeship involved mentoring young people and telling them about the dangers of getting involved in crime.

He has run anti-knife campaigns and his work has taken him to Germany to speak to young people.

Mr Sewell will complete his level three qualifications this year, allowing him to manage youth centres.

His aim is to set up his own centre in Croydon, helping those who have just come out of prison.

The 24-year-old said: "When I was in prison I knew that I had to change my lifestyle. I wanted more from life and although I had a lot of doubters, I wanted to prove them wrong.

"I have surprised some of my closest friends with my turnaround. Prison was not a good place and I want to encourage young people away from crime."

He added: "I spent numerous Christmases in prison and my 21st birthday, I basically grew up in prison. If I hadn’t of gone there though I wouldn’t be doing what I do now, it is about turning a negative into a positive."