The Mayor's proposals to combat teenage violence before it happens appear to reflect a considered view of the underlying causes of a phenomenon which has claimed 21 young lives in the capital this year.

Mr Johnson is prepared to support organisations like army cadet forces and the Scouts, with long experience of providing structured activities that appeal to young males, and to establish new “respect” schools on Saturdays where teenagers at risk of offending could benefit from academic and sports tuition. He also wants to run parenting classes aimed at the single mothers who have difficulty handling their teenage sons. And the emphasis on showing pre-teen children the implications of carrying knives looks sound.

The funding for all this, however, is not guaranteed. The Mayor has asked TfL, the Met and other bodies to find cash from within their own budgets. He will lobby central government to make good promises it had previously made to Ken Livingstone, and he is seeking donations to his new Mayor's Fund. Knife and gun crime casts a blight of fear over many London neighbourhoods and has claimed too many innocent lives. This newspaper calls on all those now being approached for funds to show their support.

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