The grieving mother of Canonbury teen Vaso Kakko left the court room sobbing this morning as his killer described the moment he “sliced him”, leaving a wound that severed his jugular and ceratoid veins, as well as his voice box.

But Uchechukwu Ejimonye, 20 – a cannabis dealer from Holloway known by his street name Realz – told jurors at the Old Bailey he had no idea that he had seriously harmed 17-year-old Vaso.

After the incident on November 23 just before 8.45pm, he described how after running off he stuck to previously made plans to meet his friend in Haringey and began phoning around to call in his drug debts.

Paramedics and the air ambulance tried to save Vaso’s life at the scene, in a small community garden off Yoke Close on the Shearling Estate, Holloway - but he was dead within 35 minutes.

Defence barrister David Aaronberg asked whether he would have made the calls had he known he had seriously injured someone moments before, and he replied: “Never. I don’t think I’d have even been in the mood to talk.”

Ejimonye, who was arrested seven days later in Bognor Regis, Sussex, denies murder.

But he admits possession of the knife and does not dispute he stabbed Vaso, claiming he acted in self defence and that the incident was “part of a feud between him and the victim”.

Ejimonye claims that Vaso had stabbed him with a “Rambo-style knife” and pulled a taser on him during an argument weeks before his death on Ejimonye’s birthday.

He next bumped into Vaso unexpectedly on Caledonian Road the night of the incident, where he had gone to meet a friend who had promised to supply him with cannabis to sell.

Ejimonye, who began carrying a knife in 2015 after being hospitalised after being stabbed, said: “I didn’t realise it was him immediately, I wasn’t wearing my glasses, but I saw his distinctive jacket.

“He brought out his knife telling me to come to the back roads and I bought out my knife to get it over and done with.”

One of their friends told them to put the knives away, and they walked with four friends to Yoke Close 10 minutes away.

Ejimonye said: “Because of where the argument started, we wanted to go to somewhere quiet and deal with the situation.

“The argument didn’t stop. We was both calling each other names. There’s a word ‘moist’ that means ‘soft’ – ‘you’re not on my level’. He was saying: ‘You’re not a big man like I am.’

“I just said: ‘You think you’re bad because you stabbed me.’”

When he asked Vaso why he was making phone calls, Ejimonye claims he replied: “I’m going to get a fat shank for you.”

“I said: ‘What’s wrong with the knife you’ve got now?’ and he said: ‘I’m not going to get a fat shank – I’m going to get a baseball bat for you and make you dumb’,” said Ejimonye.

Once in the community garden, the pair were left alone by their friends, who had gone to make phone calls, look for a lighter and pop to the shops.

Ejimonye claims he saw Vaso reach inside his jacket where he believed his knife was. Thinking he was about to be stabbed, he added, he too pulled out his knife.

He said: “I felt at that moment I had to try to get at him first so he can back off.

“I went for my knife. It was on my waist. I took it out and went for his face.

“I wanted to try to slice him first before he stabbed me.”

Ejimonye said he was surprised to hear later that he had stabbed him in the back too, but conceded: “It could only have been me.

“This all happened really quickly – I can’t remember swinging it twice at him.

“The only reason why I might have gone for his back was I thought when he was running down the slope he might have turned around and tried to attack me.

“I ran off, before he had the chance to attack me. He was touching his face checking if there was blood.”

The trial continues.