Sudesh Amman was fascinated with dying “in the name of terrorism” and one of his life goals was to be a martyr.
The supporter of so-called Islamic State (IS) grew up in Harrow, living with his mother and five brothers.
He was aged just 17 when he began collecting terrorist material in 2017.
That same year he also racked up convictions for possession of an offensive weapon and cannabis.
He became obsessed with carrying out such an atrocity using a knife, the Old Bailey heard when he was sentenced a little over a year ago for possessing and disseminating terrorist material.
Then aged 18, he smiled and waved at the public gallery as he was jailed for three years and four months on December 17 2018.
Judge Mark Lucraft QC, sentencing, said Amman had a “very concerning series of offences”, describing some as “particularly troubling”.
Police told how he shared graphic terrorist videos online and stockpiled instructions on bomb making and knife attacks.
Just over a year later the science and maths student carried out the attack in Streatham near the bail hostel where he had been staying after being released from prison just weeks ago.
To neighbours in his hometown , he was seen as a “pretty average guy” although one warned he talked about being a terrorist when he was young.
He was arrested on May 17 2018 within 24 hours of counter-terrorist police launching an investigation into his activities after he was reported by a Dutch blogger who identified extremist material in a Telegram chat in April 2018 by an account holder known as @strangertothisworld.
Prosecutor Kelly Brocklehurst later told the court there was a photo of a knife and two firearms on a Shahada flag bearing Arabic words which mean “armed and ready”.
Police found almost 10 terabytes of data on his laptop, mobile phone and other digital devices and established Amman was the account holder
He is clearly someone with sincerely held and concerning ideological beliefsProsecutor Kelly Brocklehurst on Sudesh Amman
An air gun, a black flag and a combat knife were seized from his home when he was arrested.
The blogger told police he believed Amman had also posted a link to a pro-gay rights speaker who frequented Speakers’ Corner in Hyde Park which called on others to “unite together to attack one another”.
Amman’s stash of manuals on bomb-making, knife-fighting and close combat included the titles Bloody Brazilian Knife Fighting and How To Make A Bomb In Your Kitchen.
Police found a notepad in the North West London College student’s home, in which the phrase “life goals” had been scrawled.
“Top of the list, above family activities, was dying a martyr and going to ‘Jannah’ – the afterlife,” Alexis Boon, then head of the Metropolitan Police Counter Terrorism Command, said after he was jailed.
He described Amman as having a “fierce interest in violence and martyrdom” and said he was fascinated with dying “in the name of terrorism”, adding that the case was “a reminder of the need to be vigilant to signs of radicalisation and report it”.
Amman, who had then lived with his family in Harrow, north-west London, posted al Qaida propaganda on a family WhatsApp group, exposing siblings as young as 11 to graphic material, and had shared bomb-making literature via Skype chat.
He had told his girlfriend of his wish to carry out acid attacks and that he preferred the idea of a knife attack over using bombs.
Mr Brocklehurst said: “The defendant had discussed with his family, friends and girlfriend his strong and often extreme views on jihad, the kuffar, and his desire to carry out a terrorist attack.
“Much of his fascination with conducting an attack was focused on using a knife but reference was also made to committing acid attacks on mopeds.”
The prosecutor said Amman’s interest in Islamic extremism and IS in particular was “more than a mere immature fascination with the taboo and with graphic violence”.
He added: “He is clearly someone with sincerely held and concerning ideological beliefs.”
Hossein Zahir QC, defending, described him in court as not someone with settled and firmly held views but “a young man casting around” who has concerns about violence towards Muslims.
Amman admitted six charges of possession and seven of disseminating terrorism documents – and was given credit by the judge for his early guilty pleas.
But he denied three further counts which were ordered to lie on court file.
One of his neighbours Jignesh Khomani, a 20-year-old mechanical engineering apprentice, described Amman as “a pretty average guy”, telling the PA news agency: “There were no signs of anything (like this). He was just normal really.”
But a teenager, who did not want to give her name, said she knew him from the neighbourhood when they were children and claimed Amman would say, “I am going to be a terrorist”, but people thought he was joking.