Iraqi Ahmed Hassan, who claims to be aged 18, pretended to engage with the anti-terrorism Prevent scheme as he plotted mass murder in the UK capital.
He made a bomb with 400g of “Mother of Satan” explosives and 2.2kg of shrapnel while his unsuspecting foster parents were on holiday in Blackpool.
The Old Bailey heard he wanted to avenge the death of his father in Iraq and was “disappointed” when the bomb only partly detonated in a huge fireball.
A jury rejected his explanation he only wanted to act out a fantasy like the Tom Cruise film Mission: Impossible and convicted him of multiple attempted murder.
He made no reaction as Mr Justice Haddon-Cave handed him a life sentence with a minimum term of 34 years.
The judge said the defendant was a “dangerous and devious individual” who quietly went about plotting his attack with “ruthless determination and almost military efficiency while pretending to be a model asylum seeker”.
He told Hassan: “Your intention that morning was to kill as many members of the British public as possible.
“I’m satisfied you were determined to create as much death and carnage that day as possible.”
Hassan was motivated by Islamic State extremism, “deep-seated hatred” of Britain, revenge for the death of his father and anger at continued bombing in Iraq.
For nearly two years, the highly intelligent college student had lived a “double life”, the judge said.
Hassan had been shown “every kindness” since he arrived in Britain yet harboured “dark thoughts” and significant hatred and animosity towards the country that took him in.
The judge said: “One can only imagine the sense of betrayal felt by all those at Barnardo’s and Brooklands College whom you duped.”
He was satisfied Hassan had trained with IS in Iraq, as he told British immigration officials, and was older than he purported to be.
The judge paid tribute to the victims whose “poignant and eloquent” statements were read in court.
The trial had heard how Hassan arrived in Britain illegally in 2015 and told officials he had trained with IS.
He was referred by Barnardo’s and Surrey social services to Prevent, but kept his murderous plans a secret.
In what the judge said was a “remarkable act of cynicism”, he used his student of the year award of a £20 Amazon voucher to buy one of the key chemicals online.
The night before the bombing, his foster father Ron Jones went to find out why Hassan was not sleeping, unaware he was sitting next to the highly unstable TATP explosives.
On the morning of September 15, Hassan left his home and caught a train to Wimbledon carrying his bomb inside a Lidl bag.
He set the timer on the District Line and got off one stop before the bomb partially exploded on the floor of the carriage at Parsons Green.
Twenty-three passengers suffered burns, with some describing their hair catching fire and their clothes melting in the blast.
Another 28 suffered cracked ribs and other crush injuries in the stampede to get out of the platform on a narrow stairway.
Hassan destroyed his phone and changed into a Chelsea football shirt as he fled London with more than £2,000 in cash but was picked up by police at the Port of Dover the next day.
Hassan’s foster parents Penny and Ron Jones, who were awarded an MBE in 2010, did not give evidence in the trial.
Afterwards they said authorities should have warned them to look out for signs of radicalisation.
Mrs Jones told ITV News: “I am cross with him for what he’s done, and that he’s done this in my house makes me feel very, very betrayed, I can’t help that. Because he’s such a bright and intelligent child, he’d got a good future ahead of him.”
A review of Hassan’s dealings with Prevent is underway.