(L to R) Tanvir Hussain, Abdulla Ahmed Ali and Assad Sarwar were found guilty
Security staff and police were racing against time when they foiled a plot to blow up airliners, experts have said.
Scotland Yard's counter terrorism chief said the arrest of the three would-be bombers was "a relatively close thing".
The operation also had to be speeded up after alleged US pressure led to the arrest of a man linked to the trio.
On Monday, Abdulla Ahmed Ali, 28, Tanvir Hussain, 28, and Assad Sarwar, 29, were convicted of conspiring to activate bombs disguised as drinks.
John McDowall, head of the Metropolitan Police's Counter Terrorism Command, said of their arrest: "It was a relatively close thing. It wasn't something that we never felt that we had control of. But our interests are always the interests of public safety."
We couldn't gamble with the prospect that if the cell we were watching was alerted... then all the things we'd built up... would have been lost potentially
Andy Hayman Former head of Met police specialist operations
UK intelligence officers believed the plot was directed by al-Qaeda figures in Pakistan, including a British man - Rashid Rauf - from Birmingham, now thought to be dead.
The White House is suspected of putting pressure on the Pakistanis to arrest Rauf in 2006, which in turn forced the hands of the British, BBC defence correspondent Gordon Corera said.
Michael Clarke, director of defence think tank the Royal United Services Institute, said Rauf was picked up after the US secretly dispatched an envoy called Jose Rodriguez to Pakistan.
He told BBC Radio 4's Today programme: "The British were hopping mad about that because it meant... they had no alternative but to move in on this plot before all the evidence was as mature as possible.
"There is a general belief in British security circles that the dispatch of Rodriguez to Pakistan came straight from the White House."
Officers from Scotland Yard's Counter Terrorism Command had what they say was "good coverage" of the suspects and were waiting for more definite evidence before acting.
Scotland Yard's former head of specialist operations, Andy Hayman, said securing the arrests from a "standing start" after Rauf's arrest was a "very difficult challenge".
He told the BBC: "We couldn't gamble with the prospect that if the cell we were watching was alerted by that arrest, then all the things we'd built up along with other colleagues from the security services would have been lost potentially."
Mr Hayman also said he believed they foiled "our UK 9/11".
At the time of his arrest, ringleader Ahmed Ali had identified seven US and Canada-bound flights to blow up over the Atlantic within a two-and-a-half-hour period.
The economic consequences would have been very, very severe.
Sir Ken Macdonald Former head of CPS
Sir Ken Macdonald, former head of the Crown Prosecution Service and Director of Public Prosecutions, said the plot would have caused "mass murder on an unimaginable scale".
He told the BBC: "If this plot had succeeded we would have had air travel paralysed for a considerable period, we would have had serious damage to trade relations between the US and UK.
"The economic consequences would have been very, very severe. This was by some way the most serious terrorist plot during my five years as DPP."
Former US security chief Michael Chertoff's reaction
Prime Minister Gordon Brown has praised the "professionalism and dedication" of the British authorities involved in the case.
His spokesman said: "The prime minister wishes to express publicly his gratitude to the police, security and intelligence agencies and all those involved in the work they did.
"Their professionalism and dedication prevented lives being lost in this country to terrorism."
The verdicts were a vindication of Britain's intelligence efforts, former security minister Tony McNulty added.
Mr McNulty told the BBC: "There were many, straight after these arrests, who were saying 'Oh, it's just another attack on the Muslim communities, it's just another plot that will be seen to be not quite what the authorities are saying'."
The convictions were, he went on, "a real vindication of a lot of effort by a lot of people - security services, police, and equally the Crown Prosecution Service for having the courage to go back when the juries who were hung last time and say 'Look, hold on, we think there is something here, we need to go further'."
Security officials on both sides of the Atlantic believe the men wanted to kill thousands in the air and possibly more on the ground in a wave of attacks causing more devastation than the 11 September 2001 attacks in New York.
The arrests of the plotters in August 2006 caused chaos to international aviation and prompted the current restrictions on liquids. It was the UK's biggest terror investigation.
Four other men were found not guilty of involvement in the suicide bomb plot. The two trials and operation cost an estimated £35m.
Airline terror plot: The evidence
Abdulla Ahmed Ali, Tanvir Hussain and Assad Sarwar were arrested in August 2006. They were each accused of two charges of conspiracy to murder using home-made explosives.
All three were found guilty in an earlier trial of conspiracy to murder involving liquid bombs - but that jury could not decide whether their plans extended to detonating the devices on planes.
Now a second jury has decided that such a terror plot did exist.
The prosecution alleged that the three ringleaders planned to explode home-made bombs disguised as soft drinks on seven trans-Atlantic flights from London's Heathrow airport.
1. 1415 UA931 LHR-SAN FRANCISCO (United Airlines)
2. 1500 AC849 LHR-TORONTO (Air Canada)
3. 1515 AC865 LHR-MONTREAL (Air Canada)
4. 1540 UA959 LHR-CHICAGO (United Airlines)
5. 1620 UA925 LHR-WASHINGTON (United Airlines)
6. 1635 AA131 LHR-NEW YORK (American Airlines)
7. 1650 AA91 LHR-CHICAGO (American Airlines)
During their investigation police found equipment that could have been used to make bombs in King's Wood, High Wycombe, and in Forest Road, east London. Assad Sarwar, the quartermaster, bought a suitcase to store bomb parts in the woods near to his home. There, he hid bottles of hydrogen peroxide, also known as hair bleach. This chemical was the key ingredient for the home-made bombs.
At the bomb factory in east London, the ringleaders experimented with the design of their devices which were to be disguised as soft drink bottles. The small bombs would then be smuggled in hand luggage through airport security.
The theory of bomb construction is detailed above, but precise details shown to jurors have been omitted.
This video simulates the damage caused by a liquid bomb to a commercial airliner. The BBC used a qualified explosives engineer, Sidney Alford, to construct the devices to demonstrate their likely effect on an aircraft fuselage.
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