It was an unprecedented surveillance operation involving hundreds of police officers, and a plot that prosecutors said was unparalleled in its terrible ambition.
But it has taken two prosecutions to prove beyond reasonable doubt that a plot which changed the nature of air travel was genuine. Now, the British men behind a plan to launch suicide bomb attacks on a succession of transatlantic airliners are facing a life in jail.
Almost 18 months ago, prosecutors first told a jury of an ingenious plan to create liquid bombs disguised as soft drink bottles. It was this plot that in August 2006 brought chaos to international aviation as liquids were almost entirely banned from hand luggage on planes. And those restrictions, and the huge costs they cause, remain in place today.
But while the first jury at Woolwich Crown Court convicted the three ringleaders of conspiracy to murder, it stopped short of concluding their targets were planes.
OPERATION OVERT IN NUMBERS
26,000 exhibits collected
102 property searches
80 computers and other devices seized
226 seized from inside internet cafes
500 Floppy disks
14,000 Gigs of data
Countries visited: Japan (because of the type of batteries they had), Pakistan, South Africa, Mauritius and Belgium.
Source: Met Police
Now, after a lengthy retrial, a second jury has found the three men accused guilty of targeting ordinary travellers.
A jigsaw of extraordinary evidence had finally come together to justify the massive delays at airports and moments of high political tension between governments tracking terror plots around the world.
The race to bring to justice Abdulla Ahmed Ali, Assad Sarwar and Tanvir Hussain took place over a matter of weeks. But the story of what the police came to call Operation Overt began in the aftermath of al-Qaeda's 9/11 attacks on America.
As US forces poured into Afghanistan, the decades-old refugee crisis worsened. The Islamic Medical Association, a charity shop in Clapton, east London, raised money and collected equipment to send to refugee camps on the Pakistan-Afghanistan border.
AHMED ALI'S TRAVELS
Feb 2003: Pakistan refugee work
Jan 2004: Pilgrimage to Mecca
Aug 2004: Pakistan refugee work
(In Pakistan at the same time as the 7/7 and 21/7 ringleaders)
Jan 2005: Returns to UK
June 2005: Back to Pakistan
May 2006: Final visit on family business
Ali and Sarwar went to deliver aid to the refugee camps - and their experiences radically altered their world view.
Abdulla Ahmed Ali, the ringleader of the group, was shocked by the appalling conditions. His anger was compounded by the failure of the 2003 mass protest against the Iraq war.
The anger felt by men like Ahmed Ali turned him against the UK and America and he turned to radical Islamists who were increasingly calling for attacks on Britain.
As the security services watched some of the people moving in these circles, Ahmed Ali became an object of interest.
MI5 officers twice approached Arafat Khan - Ahmed Ali's old school friend and one of the co-accused found not guilty of the plot. Officers told Khan that they needed help working out who was a danger in east London. He refused to become an "asset".
But when Ahmed Ali himself returned from Pakistan in June 2006, investigators were sufficiently interested in him to secretly open his baggage before it got through to the arrivals hall.
Shopping trips: Sarwar bought suitcase to store bomb parts in woods
Inside they found an unusual powdered soft drink, Tang, and a large number of batteries.
The find was out of the ordinary - and officers decided they needed to know more. In the coming weeks, the Metropolitan Police and MI5 mounted a surveillance operation that would grow into the largest ever conducted in the UK. By the time of the arrests, 220 more police officers had been drafted in from other forces.
During this time Ahmed Ali and Assad Sarwar, his deputy based in High Wycombe, Bucks, were sending e-mails to Pakistan. These coded messages only became clear after the arrests; they were thinly veiled communications to their jihadist contacts.
The orders came back to push ahead with the project - or "presentation" as Ahmed Ali described it. They needed to look for willing volunteers and watch out for surveillance.
The e-mails were not available to the prosecution in the first trial - but became a critical part of the story second time around.
Sarwar, convicted at Woolwich Crown Court as the "quartermaster" of the plot, was watched busily buying items that did not fit with his daily needs - and which had a potentially deadly context.
Bomb factory: Ordinary flat in East London
His e-mails talked about acquiring Calvin Klein aftershave for a business opportunity - but instead he was buying hydrogen peroxide, a legitimate chemical that can be turned to a deadly use. The quantities of aftershave he referred to bore a striking similarity to the quantities of chemicals he amassed.
When MI5 secretly broke into the east London flat being used by Ahmed Ali, they were alarmed by what they saw. It appeared to be a bomb factory - but a very strange one.
On 3 August, MI5's tiny camera and microphone recorded Ahmed Ali and co-accused Tanvir Hussain, also convicted, constructing odd devices out of drink bottles. If these were bombs, why were they so small?
The security services started picking up the clues. Some of the men were heard reviewing numbers, and talking of "18 or 19". Did that mean 19 devices, 19 targets or perhaps 19 conspirators?
Then a surveillance team watched Ahmed Ali in an internet cafe, researching flight timetables for two hours.
It all came together. The bombs did not need to be big - they just needed to be made from small parts - and powerful enough to rip a hole in an airliner's fuselage.
The effect of a liquid explosive on an aircraft fuselage
In 2001 Richard Reid tried to bring down a jet with a small explosive device in his shoe.
Counter-terrorism chiefs had been expecting jihadists to use small bombs again - and they had also not ruled out a mass mid-air attack after one such plot was stopped in Asia in 1995. Ahmed Ali's scheme appeared to cover both possibilities.
Since 2001, there have been a series of extremely dangerous plots in the UK - and the Operation Overt convictions are a major milestone in these huge trials. The plot is believed by intelligence sources to have been directed by Al-Qaeda.
Why did all these men turn to violence?
The reason can be found in their own words, writings and martyrdom videos; a simple and seething anger over British and American foreign policy, and an overwhelming belief that Muslims were its helpless victims.
Now, following two very difficult trials, these men all face life sentences.
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