The Metropolitan Police Commissioner said parents must confront their children over weapons in the same way as drugs and excessive drinking. He said his force is "bending every sinew" and using every available resource to stem the youth violence crisis it faces.

Speaking at New Scotland Yard, he said: "I want to express my deep regret at the murder of Robert Knox and the murder of Jimmy Mizen and Lyle Tulloch in recent weeks and again express absolute determination on behalf of the Met to try and take these knives off the streets. Parents have a duty now to be asking their teenagers: 'Are you involved in this knife carrying?'"