A teenager snared by secret agents as he plotted a bomb attack on the anniversary of the 9/11 atrocity is facing a possible life sentence.
Haroon Syed trawled the web to find a busy area in the capital such as Oxford Circus or an Elton John concert in Hyde Park to launch a mass casualty attack.
He also tried to get weapons online, including a bomb vest or explosives.
The 19-year-old was caught chatting with officers from the British Security Service who posed as fellow extremists who could help him source the weapons.
Syed, from Hounslow, west London, is due to be sentenced at the Old Bailey on Monday after previously pleading guilty to preparation of terrorist acts between April and September last year.
Judge Michael Topolski QC has said he faced a "discretionary life sentence".
His older brother Nadir Syed, 23, was jailed last year after he was found guilty of plotting to carry out a Lee Rigby-style beheading around Remembrance Sunday in 2014.