The timing of the bombings, on the opening day of the G8 Summit, and the coordinated devastation they caused, appears to be a resounding propaganda coup for al-Qa'ida and its supporters.
For the police and the security services it was a severe failure of intelligence. The threat assessment had been scaled down just a few weeks ago and the huge security operation for the G8 meeting had been directed towards protesters in Scotland, with more than 1,500 police officers sent up from London.
Last night the biggest criminal investigation in recent British history swung into action with the police and the security services carrying out forensic tests, checking CCTV cameras, and examininglists of suspects. Law enforcement agencies in Europe, the US and the Middle East were contacted immediately.
A few clues emerged early. Two of the underground blasts had been caused by high explosives packed into containers, possibly brief cases, taken on to the trains and left there. However, the bomb which ripped the roof off the double-decker bus in central London may have been detonated by the person carrying it. Police say it could have gone off accidentally while being transported for another Tube attack but they were also considering whether it was the first ever suicide bombing in Britain.
Suicide attacks have become a common tool for a number of insurgent groups, especially Islamists, the world over. . The United Kingdom had been spared this during the long IRA campaign, but all this may change with new protagonists.
The attacks were designed to cause the maximum number of casualties at the height of the morning rush hour at King's Cross in the north, Edgware Road in the west and Liverpool Street in the east. The bus bomb could, say the police have been intended for a station to the south.
In the space of 56 minutes there were at least 37 killed and 700 casualties. Within hours responsibility was claimed on an Islamist website by a group calling itself The Secret Organisation of al-Qa'ida in Europe. The bombings were, it said, in revenge for "massacres Britain committed in Iraq and Afghanistan".
A group, using the same name, claimed responsibility for the last major terrorist attack in Europe - the coordinated bombings of commuter trains in Spain on 11 March last year that killed 191 people. Two days after the blasts a video was found in a dustbin outside a mosque with a statement from Abu Dujan al Afghani, who described himself as the group's spokesman.
But British and US officials as well as security analysts stressed yesterday that there was no proof that the group actually existed and had carried out the attacks.
The website statement said: "Rejoice, Islamic nation. Rejoice, Arab world. The time has come for vengeance against the Zionist crusader government of Britain in response to the massacres Britain committed in Iraq and Afghanistan.
"The heroic mujaheddin carried out a blessed attack in London, and now Britain is burning with fear and terror, from north to south, east to west. We warned the British government and the British people repeatedly. We have carried out our promise and carried out a military attack in Britain after great efforts by the heroic mujaheddin over a long period to ensure its success."
The statement went on to warn the Danish and Italian governments that, "they will receive the same punishment if they do not withdraw their troops from Iraq and Afghanistan."
There is no evidence that the string of Islamist bombings in recent years including Bali, Istanbul, Riyadh, Casbalanca and Madrid were carried out by al-Qa'ida members acting on the direct orders of Osama bin Laden. Instead, they appear to have been carried out by local cells of sympathisers.
There is, however, plenty of evidence of collusion between militants within Europe and Spanish police have claimed there are connections between the group which carried out the Madrid bombings and Britain.
Three men allegedly implicated in the Madrid bombings are said to have British links, including a Syrian living in London. His brother was arrested by police in Spain accused of sheltering some of the bombers and was also questioned about suicide bombings in Casablanca which killed 45 people.
Abdelkarim el Mejjati, also known as Abu Elyas, vanished from Spain a few days before the Madrid bombings and was sighted in London. He was convicted in absentia in Tunisia for the Casablanca bombings.
An alleged ringleader of the Madrid attack, Mustapha Setmarian Nassar, also Syrian-born, lived in north London in the late 1990s and is said to have been a visitor to the mosque at Finsbury Park. There had been sightings of him in London after the Madrid bombings, although US authorities, who have placed a $5m bounty on him, maintain he is now in Iraq where he has established links with the Abu Musab al-Zarqawi, the Jordanian-born militant who runs al-Qa'ida in Iraq.
Nassar is known to have associated with Abu Qatada, one of detainees released from Belmarsh in March this year, while he lived in London. Spanish authorities claim that Qatada, described by a British judge as a "truly dangerous" individual, also had links with Abu Dahdah, another Syrian living in Spain who was arrested there on suspicion of recruiting bombers.
The security agencies maintain, however, that there is no reason for foreign operatives to come here to carry out attacks because there is no shortage of home-grown activists mainly from the Pakistani community.
MI5 say that around 3,000 British Muslims went through al-Qa'ida training camps in Afghanistan and Pakistan, although the vast majority have played no active part in terrorism. Tony Blair has spoken about "several hundred" trained al-Qa'ida operatives in Britain, a figure supported by the Scotland Yard Commissioner Sir Ian Blair.
With yesterday's attack came the reminder of the message delivered by IRA bombers after the assassination attempt on Mrs Thatcher in Brighton ."You have got to be lucky all the time, we have got to be lucky just once."
The global campaign of terror
The attacks of 11 September 2001 in America were Osama bin Laden's most infamous acts of terrorism. Trained Islamic suicide hijackers took over and crashed four civilian aircraft. About 3,000 people were killed.
On 23 December, the British "shoe-bomber" Richard Reid attempted to blow up an airliner on its way to Miami.
On 12 October 2002, two bombs destroyed a nightclub in an Indonesian resort on Bali, killing 202 people, including 88 Australian holidaymakers and 33 Britons. In May 2003, 45 people were killed - including 12 attackers - by bombers in the Moroccan city of Casablanca.
In the same month, Saudi Arabia was targeted by a series of bombing attacks against luxury compounds where foreigners live, which left at least 34 people dead. Those attacks were followed in May 2004 by a shooting spree and siege in the Saudi city of Khobar, leaving 22 people dead.
Al Qa'ida was also blamed for suicide bomb attacks on 15 December 2003 against two synagogues in Istanbul, which were followed five days later by attacks on British interests. The British consul general was among the 27 people killed.
On 11 March 2004, 10bombs exploded on four packed commuter trains heading for Madrid stations on the eve of a parliamentary election, killing 191 people.
Anne PenkethReuse content