London Mayor: We can't arrest our way out of knife crime

Knife crime in England and Wales is going up. Our presenter Martha Kearney has been to Harrow youth club with London Mayor Sadiq Khan to see one of the initiatives he's set up to try to tackle the problem. There she met some of the young people taking part - as well as Watford footballer Andre Gray - who has himself been stabbed. (Image: young people at Harrow youth club Credit: BBC)