They had failed to emulate their “brothers” who had murdered 52 passengers on the London transport network a fortnight before because their rucksack bombs did not explode. A fifth man had simply “bottled out” and dumped his bomb.

The idea had been to die and go to paradise. There was no plan B.

These men were not even foot soldiers. They were totally expendable, as much part of the bombs as the explosives, nails and detonators they carried on their backs. The shadowy figures who had planned the attacks, offered the ideological inspiration and supplied the weaponry were long gone. The bombers had no one to turn to.

Instead, they turned on each other. They ran to their homes, the flats in North, West and South London where they had been living on benefits and dreaming of jihad.

And they began to talk to each other on their mobile phones. Two, it appears, wanted to flee. The other two wanted to try again, but whether they had access to explosives or had the expertise to assemble new devices is unclear.

Sources close to the investigation suggest that the split in the suicide cell is being reflected in the interviews now being carried out in London and Rome.

Muktar Said-Ibrahim, 27, who is alleged to have tried to blow up a No 26 bus, and Ramzi Mohammad, the alleged Oval bomber, are understood to be answering none of the questions put to them.

One of these two, who were arrested in North Kensington on Friday, had shouted to police: “I have rights.” It seems that he is exercising his right to silence.

But the other two key suspects, Yasin Hassan Omar, 24, who was arrested in Birmingham and linked to the Warren Street bomb attempt, and Hussain Osman, 27, who escaped to Italy after his alleged attack at Shepherds Bush, are co-operating to some degree with their interrogators.

Osman has attempted, in his interviews with Italian officers in the Regina Coeli prison, to blame Said-Ibrahim for recruiting him to the bomb plot.

There may be some truth in that. Said-Ibrahim, rather like Mohammad Sidique Khan in the July 7 bombing gang, could have been the only figure to have had direct contact with the planners and organisers. It is not known whether Omar alerted police to the addresses where his accomplices were hiding but the recovery of his mobile phone provided valuable leads, enabling investigators to trace numbers and locate Omar’s contacts.

Detectives were already on Osman’s trail and there is concern at Scotland Yard that he managed to slip out of Britain on a Eurostar train last Tuesday. Relatives of the father-of-three, who lived in Stockwell, South London, were detained and led police to the suspect’s brothers in Italy.

Their telephones were subjected to traces by Italian police and a picture of his movements across Europe was built up. Last Friday police picked up Osman’s brother at an internet point near Termini station and he led them to his flat.

Osman was lying on the sofa and surrendered himself quietly. According to the Italian press he has been talking freely about his role. He has told police that his real name is Hamdi Adus Isaac and that he is Ethiopian, not Somali. He obtained false Somali papers to help him to claim asylum in Britain.

According to Italian media reports, Osman said that he met Said-Ibrahim and the other cell members in a basement gym in Notting Hill, West London. They were shown DVDs of incidents in Iraq that showed women and children being killed by US forces. But Ibrahim did not propose the bombing until the day before the attempted attack.

“The idea put to us by Muktar was to frighten the British,” Osman is alleged to have said. “We wanted to react to the climate of hostility against us Muslims after the July 7 attacks. People mocked us on the street and made fun of our women. We decided to react.”

In other leaks from his interrogation, he is reported to have said that the rucksack given to him by Said-Ibrahim contained no real explosive, only fertiliser and acid designed to produce nothing more than a big bang. He said: “But something went wrong and I injured my leg because some acid leaked out while I was carrying it.”

Many of Osman’s remarks are questionable. Sir Ian Blair, the Metropolitan Police Commissioner, has said that the July 21 bombs would have caused carnage except for one mistake in their configuration. He emphasised that the cell was not the B team.

Osman claimed that he had had no contact with the other bombers and decided to flee after being told to do so by his partner. The idea that he made an ad hoc escape is also doubtful. Osman followed a circuitous route to get to Rome and changed his phone’s SIM card several times to try to avoid detection.

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