A man who planned to attack British military personnel and travel to Syria to join the so-called Islamic State has had a bid to reduce his life sentence rejected at the Court of Appeal.

Matthew King, from Wickford, was jailed for life with a minimum of six years at the Old Bailey in June last year after expressing a desire to kill “non-believers” when he was 18.

The Muslim convert, who is now 20, was reported to the Prevent counter-terrorism programme by his mother and was described as posing an “imminent” risk when sentenced by Judge Mark Lucraft KC.

At an appeal hearing in London on Wednesday, lawyers for King said that his sentence was “manifestly excessive” and that the seriousness of his offending did not justify a life term.

But three judges dismissed his bid, stating that King was “concentrated and focused” on committing terrorist activity.

Giving their ruling, Mrs Justice May, sitting with Dame Victoria Sharp and Mr Justice Hilliard, said: “The degree of his emotional extremism together with his apparent readiness to engage in violence against non-believers remained very worrying.”

She added: “The recorder did not err in his approach to the difficult task of sentencing this young man.

“This appellant had already had opportunities to moderate his beliefs, his own mosque had attempted to dissuade him from extremism … but he persisted.”

King, who had no previous convictions, pleaded guilty in January 2023 to preparing terrorist acts between December 2021 and May 2022.

The Old Bailey heard last June that King first became interested in Islam in 2020 and had begun regularly attending a mosque in Stratford by May 2021.

But his family noticed he had become more extreme and his mother became concerned he was watching hateful material online.

He also struck up an online relationship with a girl known only as Ms A, telling her “I just want to kill people”, “I just wanna die a martyr” and “I’m going to be training for jihad”.

The pair also shared graphic plans of how they would torture, mutilate and behead marines.

Following his arrest, videos on King’s phone were found of police officers and military barracks, which barrister Paul Jarvis described as “hostile reconnaissance”.

At the Court of Appeal, Hossein Zahir KC, representing King, said that Judge Lucraft had failed to take into account the defendant’s age when sentencing.

He also said that the prospect of King committing a terrorist act was “remote” and that the risk he posed was “manageable”.

Mr Zahir said that comments made by the defendant in custody before he was sentenced, where he threatened to “behead an imam” and “kill and chop up” prison staff, were “sometimes intemperate and derogatory”, but added that King was “still on the road to deradicalisation”.

But Mrs Justice May said that King was “singularly pursuing” terrorist acts and that Judge Lucraft was “plainly entitled” to pass a life sentence.

King, who attended Wednesday’s hearing through a video link from prison, showed no emotion as his appeal was dismissed.