Within days of the first bombs going off, the flat where the men stored the materials and assembled 12 devices was under surveillance by MI5 officers, the jury heard.
But after two of the men left the north London flat to allegedly plant the last two bombs, officers twice lost the men with the result that they were unable to prevent the attacks.
Hours after the bombs exploded, however, the two men, Derek Doherty, 23, and Gerard Mackin, 33, were trailed to a motorway service station hundreds of miles from London and eventually arrested. The third man, Thomas McAuley, 37, was arrested at his flat in Tottenham, where a search uncovered 10 detonation and timing devices, Semtex explosives, and a loaded revolver with spare ammunition, the jury heard.
All three deny conspiracy to cause explosions likely to endanger life or seriously damage property between 1 January and 10 October last year. The trial is expected to last six weeks.
Nigel Sweeney, for the prosecution, told the jury in Court Two, which was guarded by armed police officers in bulletproof vests, that McAuley, accompanied by Mackin, had picked up a heavy consignment from Newry, Co Down, and signed for it in a false name on the day before the bombing campaign started on 1 October.
That night and the following morning, three bombs exploded on Finchley Road, near Swiss Cottage, causing extensive damage to property. The fourth device failed to go off, and when examined was found to be typical of an IRA bomb save for the difference that wires from the timing and power unit to the detonator were soldered together, a technique not seen before.
Mr Sweeney said that three days later, five out of six bombs planted at Hornsey, Archway and Highgate exploded, again severely damaging property. The one which failed displayed the unusual soldered technique.
Finally, two devices went off on 8 October, one at Staples Corner and the other at West Hampstead, wrecking a number of business premises. As in all the explosions, no one was seriously hurt.
However, the jury heard how one man had a lucky escape when he pulled one of the devices in Highgate from its black plastic bin-bag and began fiddling with it, not realising what it was.
Believing he had stumbled on some kind of home-made doorbell, he tried to remove the batteries from the timing and power unit after the lid fell off, but when he failed, he walked off leaving the device.
Only when he heard the explosions did he realise what it was and he went to the police.
'The prosecution allege all three defendants played a part in the campaign to cause explosions,' said Mr Sweeney. 'We also allege that McAuley's small flat at 1 Lido Square, Tottenham, was used for storage of bombing equipment and other items in the campaign and making of the bombs.'
The trial continues today.Reuse content