A Question Time-style event held by a Camden children’s charity saw top cop Raj Kohli speak about the need to reach out to “grieving friendship groups” after young people are killed.
Ch Supt Kohli was the guest of 300-year-old charity Coram at its King's Cross base.
A panel of youth workers, young people and experts including Shirley Cramer, chief executive of the Royal Society for Public Health, discussed how a "public health" approach and authorities winning the trust of vulnerable young people could stem the tide of knife crime casualties.
Ch Supt Kohli, who is the BCU (basic command unit) commander of Camden and Islington police, said: "For me, every arrest is a failure.
"When a young person dies the public authorities know how to deal with families, but we forget the friendship groups."
He asked the panel: "How can we better look after them? When you are in mourning, you make decisions you otherwise wouldn't."
In response, Ms Cramer cited an American programme, and said: "There, they work to look at the social connections. They have mapped out the friendships. They know who are involved in gangs so they know how to find them."
And one young member of the panel - Marsha - added: "We as young people need to know that we can have trust in the police."
Other panellists included Junior Smart, a youth worker who founded the SOS project. It works across London, including in Camden, to help young people out of gangs.
He said authorities need to show "they are sincere". "When young people realise they can talk to us in a safe way," he said, "they do."
The meeting was opened by members of south London's Rap Club, who performed tracks referencing the difficulties of growing up in London.
Later in the meeting Ch Supt Kohli defended the Met's use of section 60 stop and search orders.
He said he "didn't like it as a power" but that when section 60 orders were used in the aftermath of violent crime "we find that, in our experience, people are laying down weapons".
He added: "That's what I want to happen. It'll not stop people stabbing each other, but it'll stop them stabbing each other at that time." But Mr Smart said: "As soon as they are criminalised, their options change. We've got to see each child as our own."
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