John Twomey, 62, Peter Blake, 57, Barry Hibberd, 43, and Glenn Cameron, 50, were convicted at the Old Bailey of charges relating to the warehouse heist in February 2004.

New laws meant the trial could be held in front of a judge sitting alone after the Court of Appeal ruled last year there was a "very significant" danger of jury-nobbling.

The historic trial, which campaigners said set a dangerous precedent, was the fourth time the defendants had faced court proceedings over the raid after the previous trials had collapsed.

The court heard that a gang of masked robbers, wearing high-visibility jackets and dark woollen hats, carried out the raid on the Menzies World Cargo warehouse, planned with the help of insider Darren Brockwell, who later turned supergrass (police informer).

Five of the robbers were armed with handguns and a sixth carried a Heckler & Koch 9mm firearm similar to those used by police, the Press Association reported.

During the holdup, 16 members of staff were tied up and threatened while one was shot at by Blake as he tried to escape and raise the alarm.

Robbers took 1.05 million sterling pounds and the rest of the cash in Swedish, Danish, Norwegian and Australian currency, some of which were changed at foreign exchange centers in central London in the following weeks.

The raid was described by prosecutor Simon Russell Flint as a "professionally planned and professionally executed armed robbery.” The court heard that Twomey, Blake and Hibberd, who the court heard were "experienced career criminals,” carried out the raid with Twomey's brother-in-law Cameron, and two other men who have yet to be brought to justice.

All four defendants were found guilty of robbery and having a firearm with intent to commit robbery.

Blake was also found guilty of attempting to cause grievous bodily harm and possession of a firearm with intent to endanger life. Hibberd was cleared of 13 charges on unrelated firearms offenses.

The latest trial began in January at London's Royal Courts of Justice but was switched to the Old Bailey last month after Blake went on the run after escaping from court.

He handed himself in five days later.