A British man jailed for plotting to blow up a plane has given taped evidence in the trial of an al-Qaeda operative accused of trying to bomb New York's subway system.
The Brooklyn courtroom was silent as Saajid Badat, the ex-grammar school boy from Gloucester, described meeting Osama Bin Laden in Afghanistan soon after the 9/11 attacks.
Bin Laden was justifying Badat's planned mission to blow up an aircraft - and himself - with a shoe bomb. The al-Qaeda leader told Badat how more attacks like 9/11 "will help us ruin the US economy".
Ten years later and Bin Laden is dead, while Badat thought better of being a shoe bomber and turned supergrass instead.
Now Badat has become the first terrorist convicted in Britain to testify at a trial overseas.
Badat was convicted in 2005 of plotting to blow up an aircraft - he was conspiring with Richard Reid - and received a reduced sentence in return for co-operating with the British authorities.
Languishing in jail with a parole hearing due in 2008, Badat decided to step up his level of co-operation by agreeing to testify against al-Qaeda leaders.
On 29 March this year Badat gave videotaped evidence in Britain to US prosecutors; that two-and-a-half hour testimony was played on Monday in the trial of Adis Medunjanin.
The testimony provided an insight into life in the al-Qaeda training camps in Afghanistan circa 2001, and painted a portrait of the studious young man from Gloucester who became radicalised.
Badat outlined his journey from Gloucester to Afghanistan via the "Tooting circle" in London, where he learned about taking up arms in the name of Islam.
"It was almost the glamour factor of it, drawing me in," admitted Badat, who listened to an audio tape called In the Heart of Green Birds about people killed fighting in Bosnia.
Life in an al-Qaeda training camp in Afghanistan included time in the "media centre", where propaganda videos were translated from Arabic into English.
Wearing a smart grey suit with a bright blue tie, his head shaved completely bald, Badat's testimony was played on a series of TV screens in the Eastern District Court.
The softly spoken Badat recounted his meetings with Bin Laden and with Khalid Sheikh Mohammed, the mastermind of the 9/11 attacks.
Sheikh Mohammed told Badat and Richard Reid "how to interact with each other", he said.
'Van Damm on his own'
Badat explained how he left Kandahar in Afghanistan for Karachi, Pakistan, at the end of 2001, along with Richard Reid and a group of Malaysians.
He said he gave one of his explosive shoes to the Malaysians "in support of their mission." The plan was for Badat to detonate his shoe on board an aircraft.
"I would be killed, along with everyone else," explained Badat.
But once he reached Britain, the young man decided not to go through with his "mission". He was reluctant, frightened and worried about the implications for his family.
Badat dismantled his explosive shoe and kept the component parts.
He said in testimony: "Whilst I hadn't undertaken the mission, I hadn't abandoned the principle of jihadi and so I remained armed".
Badat wrote an email to his handler: "You'll have to tell van Damm he could be on his own."
Richard Reid - aka van Damm - failed in his attempt to blow up a plane with his shoe. The investigative trail led to Badat, who was arrested and jailed.
Hearing in 2008 that Khalid Sheikh Mohammed was facing trial for the 9/11 attacks, Badat decided to give evidence against him. His motives were mixed.
In testimony, Badat admitted that he was about to have a parole hearing, and was facing US charges for the shoe-bombing plot.
He claimed to feel "almost a moral obligation to give evidence against Khalid Sheikh Mohammed".
Badat believed Sheikh Mohammed would "try to justify his actions".
He told the UK authorities he could be a voice for the "exploited hijackers" manipulated by al-Qaeda leaders and their "bullshit cause."
In returning for agreeing to testify against al-Qaeda leaders, Badat signed a new co-operation agreement in in 2009.
The benefits Badat received for turning supergrass included parole, housing, phone and internet access, unemployment benefit and courses to help him return to society.
Today he has a job - and obligations to help UK and US prosecutors.
Badat did not want to leave the UK and testify in the US, though, believing he would be arrested on shoe-bombing charges.
The question is what benefit Badat's testimony will have in the trial of Adis Medunjanin.
Badat does not seem to have met Adis Medunjanin or his associates - they were in al-Qaeda training camps in Waziristan in 2008, while Badat was in Kabul and Kandahar in 2000 and 2001.
US prosecutors seem to be hoping Badat will confirm other evidence about the general conditions in al-Qaeda training camps.
By showcasing the benefits of being a supergrass, the British authorities may hope to persuade other al-Qaeda operatives to turn against their colleagues.
But if Badat's testimony seems to have little relevance to the trial in New York, questions remain about whether it is wise to expose a supergrass to such scrutiny when high-profile prosecutions - including that of Khalid Sheikh Mohammed - are coming up?