A jury found five British Muslim men guilty on Monday of planning fertilizer-bomb attacks around London, ending a yearlong trial that linked the plotters with two of the four men who blew themselves up on London’s transit system in July 2005.
According to the evidence, revealed during the trial but made public for the first time, authorities had closely monitored meetings in 2004 between members of the two plots but never fully investigated the men who pulled off the transit attacks, which killed 56 people 18 months later. To ensure a fair trial, the judge had ordered the news media not to make the information public until after the verdict.
The revelation turned a victory for British authorities into a day of hand-wringing and recriminations over whether they had missed an opportunity to prevent the deadliest terrorist attack in the country’s history.
Within an hour of the verdict, the opposition Conservative Party and survivors and relatives of the victims of the transit attack demanded an investigation into why the authorities did not act on their surveillance.
“Whether deliberately or not, the government have not told the British public the whole truth about the circumstances and mistakes leading up to the July 7 attacks,” said David Davis, the spokesman for the Conservative Party on counterterrorism.
The connection between the two groups, both in Britain and in Pakistan, pointed to a level of organization among terrorist cells here that initially had been seen as “homegrown” and independent.
The two 2005 suicide bombers, like four of the five men convicted on Monday, were British citizens of Pakistani origin. At least some of the men in both plots were trained at military camps in Pakistan that were suspected of connections to al-Qaida operatives.
Britain’s senior counterterrorism police officer, Peter Clarke, said that the investigation showed the links that these men had with al-Qaida in Pakistan and the threat theyposed to Britain. But he made no mention of the court record showing links between the two groups.
For its part, MI5, the domestic intelligence agency, a famously secretive organization, went public to defend itself, saying on its Web site on Monday that it had never been “complacent” in investigating the 2005 transit attacks.
Last week, the head of MI5, Dame Eliza Manningham-Buller, retired and was replaced by Jonathan Evans, a Qaida specialist. The agency said the change was unrelated to the revelations from the investigation, which the authorities named Operation Crevice.
That law enforcement authorities knew of a connection between the two groups is especially embarrassing because three days after the July 2005 attacks, Charles Clarke, then the home secretary, said the attack “simply came out of the blue.”
The order of the judge, Sir Michael Astill, keeping the links between the groups secret, was lifted on Monday, as the jury delivered the verdicts after 27 days of deliberations.