Ex-gang member on why people carry out stabbings

BBC Newsnight has uncovered some of the violent imagery being shared online among young people in London.

There have been more than 50 killings in the capital this year. Last month, the head of the Metropolitan Police,

Cressida Dick, said social media platforms "rev people up" and make street violence more likely.

Here, an ex-gang member talks about why people carry out stabbings - and how violent images make the problem worse.