A 17-year-old boy has been jailed for six-and-a-half years for killing a woman “in a fit of rage” during a loud, gas-filled argument last Christmas Eve.

The unidentified teenager had argued with 22-year-old mother Kacey Clarke at a flat in Bermondsey, south-east London, and stabbed her in the chest.

The defendant was cleared of murder after a trial but was found guilty of manslaughter and sentenced at the Old Bailey on Friday.

The court was told that at the time of the murder he was on bail for a string of e-bike mobile phone snatching offences, from which he stole 34 devices worth £28,000.

Passing sentence, Judge Simon Mayo KC told the defendant: “I am sure that in anger you took a hunting knife… unsheathed it and stabbed him in the side of the chest.

“I accept that you did not intend to stab him and that your decision to do so was formed several minutes before doing so.

“I also accept that you regret your actions and that the remorse you express is genuine. “You will have to live forever with the fact that you stole Kacey’s life in that moment of anger.”

The judge noted evidence from Ms Clarke’s uncle, Steve Armstrong, who described the “huge impact” her death had had, leaving “a huge void in our hearts and lives”.

The judge said he was sure both the defendant and Ms Clarke were “under the influence” of nitrous oxide at the time of the murder.

He did not impose separate sentencing on the cell phone snatching and six counts of conspiracy to commit robbery-related dangerous driving charges.

The court was told the teenager narrowly avoided pedestrians by riding an e-bike on the pavement.

Earlier, the court heard an argument broke out over Miss Clarke’s misplaced missing car keys.

The teenager was caught on CCTV threatening to “untie” him and kill him.

The court was told Ms Clarke threw an object at the teenager and pulled out a lock of her hair.

However, the judge rejected the defendant’s claim that he had a knife in his hand before arming himself with a hunting knife in self-defence.

Police and paramedics were called just after 10pm and found Ms Clarke lying on the kitchen floor of the flat with a single stab wound to her chest.

The defendant was captured nearby approximately 45 minutes later.

The hunting knife was hidden in the railway arch by a Thames Water worker on January 17.

The boy, like the victim, was said to have a history of inhaling nitrous oxide (commonly known as laughing gas), which was classed as a class C drug in November 2023 as part of a crackdown on anti-social behaviour.

A search of the teenager’s bedroom uncovered a large collection of tin cans, the jury was told.

The court heard the defendant had a history of possessing knives and was caught with a 25cm long Rambo-style knife in an ice cream shop and with a lock knife in his waistband in a residential area.

He was convicted of a total of 25 crimes between April 2022 and September 2023.

As part of the mitigation, it was claimed that although the teenager was carrying a knife, he was not behaving in a threatening manner and Ms Clarke “had demons”.