Secret agents posing as extremists helped to catch a terrorist who was plotting to bomb an Elton John concert.
Haroon Syed has been jailed for life with a minimum term of 16 years and six months at the Old Bailey.
The 19-year-old had searched online for parts of London where he could unleash an attack, the court previously heard.
He narrowed his search to Oxford Circus as well as the singer’s concert in Hyde Park, which was held on the 15th anniversary of the 9/11 attacks last year.
Syed had tried to buy a suicide vest and a machine gun online, the court was told.
But the teenager was caught by the British Security Service who pretended to be extremists and claimed they could help source the weapons.
Syed, from Hounslow, west London, had pleaded guilty to preparation of terrorist acts between April and September last year.
His older brother Nadir Syed, 23, was jailed last year after he was found guilty of plotting to carry out a beheading attack around Remembrance Sunday in 2014.
The Old Bailey heard his brother’s arrest was the trigger for Syed’s radicalisation, and he fell under the influence of Al-Muhajiroun, the banned group linked to hate preacher Anjem Choudary.
Despite having his passport seized in 2015, Syed slipped through the net of the Prevent anti-radicalisation team.
Home Office approved de-radicalisation expert and Bradford imam Alyas Karmani told the court there should have been earlier intervention in his case.
Mitigating, Mark Summers QC said it was a ‘crude, ill-thought-out’ plan made at the behest of others.
But Mr Summers added that Syed now publicly rejected his past beliefs and condemned the Manchester suicide bombing that killed 22 people.