A teenage Islamic State fanatic who found his faith when he was 16-years-old and plotted a London terror attack was arrested after his mum reported him to Prevent, a court heard.

Matthew King appeared at the Old Bailey to be sentenced on Friday (May 12) after he pleaded guilty to preparation of terrorist acts. 

The 19-year-old staked out a British Army barracks in Stratford and a expressed desire to “torture, mutilate and kill military personnel”, Prosecutor Paul Jarvis said.

Other targets for his potential knife attack included Stratford police station, train station and magistrates' court.

The teen, from Wickford in Essex, found his faith when he was aged 16 after he left education without any qualifications having dabbled in drugs and been expelled from school, Mr Jarvis said.

King asked his mum to take him to a mosque and began watching videos about Islam, wearing traditional Islamic clothing and learning Arabic. 

The court heard that Islam initially had a positive effect on his life, but soon his behaviour become more extreme as he called his sisters slags for not dressing modestly. 

He also spoke about Islam constantly and told his mum he wanted to go to Syria with a girl from the UK who he had been talking to online.

“Mr King showed his mother videos on Instagram, some of which concerned her. One of those videos showed Muslims on horseback riding into battle overlaid with what Mr King’s mother described as motivational chanting,” Mr Jarvis said. 

King told his mum he did not believe in terrorism but she was so concerned about him that she contacted Prevent. This culminated in him being arrested.

A police investigation found that on December 22, 2021, he had registered as a customer of Knife Warehouse and searched ‘Isis knife tactical training’ and the other for ‘Isis knife tactical training video’. 

King's phone was full of violent messages, including discussions with his UK based girlfriend in which he said he wanted to "get his hands on" an American or British marine.

King had also posted a video in a WhatsApp group of a man holding a knife with the words “those who said that there is no jihad and no battle. They are lying!” and also set his WhatsApp status to “Kill the non-Muslims, wherever you see them”. 

Videos on his phone revealed that he had actively gone out to scope possible locations for his potential attack. 

King was taking lessons from Imams with extreme views in both USA and Green Street, Mr Jarvis said.

As his behaviour became more extreme King was expelled from one mosque, while other Muslims warned him about his behaviour. 

After being arrested and cautioned, King responded: “I don’t believe in the UK law, the only law I believe in is the law of Allah.” 

While King was in custody a police officer overheard King telling his mum over the phone: “I need to start training if I go to prison, I'm going to find someone in prison to train me. I need to start to eat more protein. I need to start training offensive and defensive. 

“When I get out I am going to be offensive, I'm going to be a machine. I don't care, in my eyes I haven't done anything wrong. I'm not guilty but I might plead guilty because I will get 30 per cent off my sentence. 

“Allah says he will punish the oppressors, everywhere will be Sharia law on day. When I get out, they will be controlling me, they probably won't let me have a driving license because I'll probably run people over.” 

Judge Mark Lucraft, the Recorder of London, adjourned to allow further time, so King is expected to be sentenced in two weeks.

The judge's comments at his sentencing will be broadcast on television.