A 15-year-old boy has been detained for life for stabbing to death a father-of-three outside his home with an 18-inch knife.
Described in court as an "obnoxious teenage trouble maker", the youth, who cannot be named for legal reasons, was ordered to serve a minimum term of 15 years.
The serial offender was just 14 and subject to an antisocial behaviour order (ASBO) when he attacked 45-year-old James Markham, in Chingford, east London, on 9 August last year.
He had already breached his ASBO six times before killing Mr Markham.
The boy claimed to have acted in self defence but was found guilty of murder and having an offensive weapon after a trial at the Old Bailey in July.
Ordering the boy to be detained for life on Friday, Judge John Hillen described Mr Markham as "a hard-working stonemason with his own business who worked hard to support and bring up his family".
He told the teenager: "You had not responded to attempts to divert you away from crime and antisocial behaviour.
"You regularly went missing. You have a low attendance record at school.
"Your foster parents could not prevent your behaviour. You were out of control."
"Your unhealthy interest in knives, antisocial behaviour and violence against those who challenged you all came together on Chingford Mount on 9 August last year."
Earlier, Mr Markham's mother Anita described the impact of the "wicked" murder on her family.
She told his killer: "On 9 August 2021 you stabbed my son Jamie Markham three times and murdered him.
"You had nothing to say, not even 'sorry, I did not mean it to happen'. You could not say it was an accident as you stabbed him three times.
"Taking my son's life has broken me. Jamie is in my thoughts all the time, seeing him lying there knowing I could not patch him up like when he was a kid.
"Wanting so much to help him, bring him back to us. You can never replace a child.
"When Candice (Mr Markham's partner) phoned and told me Jamie had been stabbed I had never thought that would be it and I would never be able to give him a hug and a kiss."
Previously, Crispin Aylett KC had told jurors the defendant should never have been in Chingford Mount at all on the day of the stabbing.
He said: "It is only too obvious that he cannot have thought that the criminal behaviour order was worth the paper it was written on.
"Just as he was not willing to abide by the terms of the order, so the evidence in this case suggests he was not someone who was prepared to let anyone tell him what to do."
The boy and four friends had gone into an area behind shops near where Mr Markham lived with his family.
Mr Aylett had told jurors that the victim and his family had become "increasingly exasperated" by groups of youths making a nuisance of themselves there.
A row broke out and two youths were said to have goaded Mr Markham before the defendant told a witness: "It's all right mate. He's going to get it."
Mr Aylett said: "Provoked beyond endurance, there must have come a point when Jamie Markham wanted to chase this obnoxious youth away from the area where he and his family lived - and, no doubt, make sure that he did not come back."
The stonemason armed with a drill bit from his shed ran at the boy, swinging the tool to scare him off, jurors were told.
But the boy produced an 18-inch long blade and stabbed him in the armpit, neck and back and then ran away.
Mr Markham was helped back to his flat where he collapsed and died.
The defendant had dropped his mobile phone during the fight and it was later used by police to track him down.
Mr Aylett said that the boy had a "miserable" criminal record, having been in court 12 times and convicted of 22 offences.
In mitigation, Laurie-Anne Power KC said that the boy had been affected by a lack of family presence or support as well as "neglect, abuse and feelings of trauma and loss".
She said that her client offered "sincere regret for his actions".