A 15-year-old boy has been found guilty

Harvey Willgoose, who was also 15, died when he was stabbed in the heart at All Saints Catholic High School on Monday 3 February.

The jury in a month-long trial at Sheffield Crown Court was told that Harvey was attacked following a confrontation between the pair during a lesson earlier that day.

The defendant, who cannot be named due to his age, had admitted manslaughter and possession of a knife but had denied murdering the teenager. He was found guilty by a majority verdict of 11 to one.

Following the verdict, the judge, Mrs Justice Ellenbogen, told the boy he would likely be sentenced in October.

Members of Harvey’s family were heard shouting “yes” from the public gallery, followed by tears.

During the trial, jurors heard Harvey had been attacked in the school’s courtyard after the two teenagers had quarrelled over social media in the days beforehand.

They had taken opposite sides in a separate conflict between two other pupils, which led to the school being briefly locked down on 29 January.

On the day of the fatal stabbing the defendant had claimed he could not remember the attack and that he had “snapped” and “lost control” of his actions.

But prosecutors said he “wanted to show he was hard” and “knew exactly what he was doing”, saying he had an “unhealthy interest in weapons” and had looked up “zombie killer knife” and other blades online.

The jury heard the defendant had taken pictures of himself with weapons, including a knife and axe, to warn people to stay away.

Jurors were shown CCTV footage of the stabbing and heard Harvey had been happily talking to his friends when the defendant approached him.

One teenage witness said there was an altercation and the defendant punched and pushed Harvey, causing him to stumble backwards, before pulling out a knife and stabbing him.

Another girl who gave evidence said: “We went inside to go and tell a teacher, but the teacher was frozen as well. She didn’t know what to do.”

She said: “People were running, screaming everywhere. It was, like, chaos.”

The defendant told jurors he had not intended kill Harvey or cause him serious harm.

He said he had been bullied and could “get angry quickly”, saying he had experienced racist bullying and taunts on social media about a medical condition.