Lucky loose connection prevented bomb carnage

Prosecutors said only luck and good fortune stood between the London and Glasgow terrorist car bombers and mass carnage.

The al-Qa'ida-inspired cell wanted Britain to taste the fear caused by insurgents armed with improvised explosives in Iraq and Afghanistan.

Cars laden with gas cylinders and 130 litres of petrol, each sprinkled with up to a thousand 2in clout nails, should have proved a deadly combination.

Experts said fragments of the heavy metal cylinders could have been flung up to half a mile if the bombs exploded.

But ultimately it was not luck, but a simple loose connection that saved hundreds of late-night revellers from death and injury.

Forensic investigators found an overseen gap of less than 1mm between the phones and detonators broke the initiator circuit.

Officers suspect the men chose not to use hydrogen peroxide because purchases could arouse suspicion and they were unable to obtain other explosives.

One police source said: "If both gas bottles had ignited we would have had a flaming bomb of some great velocity going through plate glass windows into a nightclub packed with people followed by a trail of flames.

"In a sense, how effective it would have been as a mass casualty device is debatable, but nonetheless it sure as hell would have sent a message in terms of public anxiety and a significant loss of life."

The jury heard how mobile phones were carefully transformed into detonators according to instructions obtained from jihadi websites.

Two unregistered pay-as-you go handsets, each from different providers in case of network problems, were placed in the West End bombs.

The design was inspired by similar bombs used to deadly effect in Madrid, Jerusalem and Bali, as well as Iraq and Afghanistan.

Only one detonator sparked, but even that was quickly snuffed out because the ambitious terrorists had simply filled the cars with too much petrol and gas.

Experts would later find there was hardly any oxygen left inside the cabins, causing the volatile gases to extinguish the flames.

Terror expert Andy Oppenheimer said mobile phone-initiated devices are notoriously unreliable and Irish terrorists took many years to refine them.

He said: "There is no such thing as a reliable bomb, even with the first atomic bombs no one knew if they would go off. And they certainly did."

Mr Oppenheimer, author of IRA - The Bombs: A History of Deadly Ingenuity, said the London Glasgow gang could not copy fighters in Iraq by obtaining explosives from discarded shells.

And he said although they could find information on the internet there were no real world contacts, commanders or supply chain to support them.

But he warned it is "only a matter of time" before Islamic terrorist perfect such bombs.

He said: "As soon as they start 'joined up terrorism' then we are in trouble, because they do have the knowledge to make these things.

"A lot of them are self-starters who have got more intention than capability which is good news for us.

"These bombs are not that difficult to put together so unfortunately it is a case of keeping on top of intelligence and the availability of materials."

The bomb design was the result of hours of painstaking internet research by Kafeel Ahmed and Bilal Abdulla.

They used jihadi forums and chatrooms as well as popular websites such as YouTube to amass a remarkable hoard of information.

Once they obtained the keys to 6 Neuk Crescent, the men transformed the suburban family home into a bomb factory.

The living room was used to prepare plastic medical syringes with double bulb filaments surrounded by ground match heads, as well as the phones.

Jurors were shown a dining table strewn with bomb-making materials including wires, circuit boards, batteries, bulbs and a soldering iron.

In the garage, the men loaded the two Mercedes. The ageing vehicles, popular with private minicab drivers, were chosen to blend in on the street.

Police spent two weeks searching the property and seized more than 1,000 exhibits after the terrorists made no attempt to conceal their tracks.

Despite their highly-educated backgrounds and meticulous preparations the men failed to make their terrorist "project" work.

Counter terrorist police suspect the bombs were Abdulla's idea following his experiences fighting with insurgents in Baghdad.

But Ahmed, who had no contact with experienced terrorists, failed to take into account how the theoretical bombs would work in the real world.

The pair also failed to realise how difficult it was to make the propane and butane gas cylinders explode.

For the Glasgow attack, the men also prepared Molotov cocktails, glass soft drink bottles filled with petrol and oil and sealed with wicks made from ripped up hospital pillowcases.

But investigators discovered they packed gas cylinders so tightly into the Jeep that flames could not heat most of their surfaces.

Witnesses at Loch Lomond noticed how the Jeep was forced down on to its suspension with the weight of the gas and petrol.

After the Jeep was rammed into the terminal and torched it reached temperatures of up to 1,500C as firefighters battled to bring the fire under control.

However, the cylinders did not explode but only depressurised, effectively turning into giant blowtorches.