UP to 400 knife-wielding teenagers could be jailed every year under new mandatory sentences announced by the Government last night after our Don't Carry, Don't Kill campaign.

Late last night, Justice Secretary Ken Clarke caved in to the pressure of our campaign with Enfield North MP Nick de Bois, by introducing new measures for four-month custodial sentences for 16 and 17-year-olds guilty of using a knife in a threatening way.

And between 200 and 400 teenagers could be sent to jail under the new measures every year, according to Ministry of Justice estimates.

Mr Clarke said: “We have already announced we are bringing in an automatic prison sentence for any adults who use a knife to threaten and endanger.

“Clearly any extension of this sentence to children requires very careful consideration.

“However, we need to send out a clear message about the seriousness of juvenile knife crime, so we are proposing to extend a suitable equivalent sentence to 16 and 17-year-olds, but not to younger children.”

But the amendment will be seen as a U-turn from Mr Clarke, who told MPs on Tuesday that mandatory sentences were “a bit of a leap for British justice” and that sentencing should be left to judges.

Our campaign had won the backing of the Prime Minister and the Home Secretary, as well anti-gang campaigners, Enfield Council and 700 Enfield residents, who signed a petition demanding action.

The amendment, which will change the law on knife crime sentencing, will be attached to the Legal Aid, Sentencing and Punishment of Offenders Bill.

The bill already includes six-month mandatory sentences for adults convicted of aggravated knife crime, and will now include at least four months' detention and training for children under 16 for the same crime.