Almost half of people charged with knife killings in London over the past three years had previously committed an offence involving a blade, new figures suggest.
Scotland Yard charged a total of 379 suspects with knife crime homicides between the start of November 2016 and the end of October last year.
Some 173 of those charged in that period, or 46%, had previously committed a knife offence, according to data released by the force.
But the proportion of previous offenders charged with knife killings fell from 71% between November 1 2016 and October 31 2017 to 37% over the same period in 2018/19.
Barnardo’s chief executive Javed Khan said: “We need to understand why those involved, including children and young people, carry knives.
“Often it’s because they are facing a poverty of hope – a future with no qualifications, no job prospects, and no role models, making them vulnerable to criminal gangs who coerce them to carry knives and deliver drugs.
“The new Government urgently needs to work with charities, education, health, youth workers, the criminal justice system and local communities to find long-term solutions to break the circle of violence.”
The figures come after 149 homicides were recorded in the capital last year, up from 133 the previous year, despite a drop nationally.
Tory London Assembly member Tony Devenish called for changes to the criminal justice system to bring re-offending rates down.
“Our prison system needs to both rehabilitate and punish knife crime offenders, which is why the new Government is entirely right to reform education in prisons and introduce tougher sentences,” he said.
“After all, some of these murders wouldn’t have been committed had the perpetrator already been behind bars.”
He added: “With the number of homicides falling outside of London but surging within the capital, it is incumbent on the mayor to drop his half-hearted approach to combating violent crime and start doing all he can to make London safe.”
A spokesman for Mayor of London Sadiq Khan said: “Tackling knife and violent crime is Sadiq’s number-one priority but it has been made much harder by a decade of austerity.
“Cuts to youth services and the chronic underfunding of police, prisons and rehabilitation services have contributed to violence increasing across the country. It is high time the Government realised that you can’t keep the public safe on the cheap”
Prime Minister Boris Johnson promised to get tough on knife crime during the general election campaign, suggesting the Tories would bring offenders to court more quickly, “within days not weeks”.
The Conservative manifesto said: “Those who use a knife as a weapon should go to prison.”
Latest figures from the Ministry of Justice show 22,306 knife or dangerous weapon offences were formally dealt with by the criminal justice system in England and Wales in the year to the end of June 2019.
Some 38% of the offences (8,446) resulted in an immediate custodial sentence, compared with 23% for the same period in 2009, while the average length of a jail sentence rose over the same period of time from 5.9 months to 8.1 months.
The proportion of repeat offenders sentenced who had previous convictions for similar crimes also rose to 29%, its highest level on record, according to the MoJ figures.