London ? A former cricket team captain and a mathematics student at a suburban university were convicted along with three other men Monday and sentenced to life in prison for plotting to stage a wave of attacks against fellow Britons that would “put terror in their hearts.”

In the conclusion of one of the longest and most expensive trials in English history, the five men were found guilty of conspiring to attack targets such as a crowded nightclub, a sprawling shopping mall and the nation’s gas and electrical grid. The plot was never carried out.

At one point, the conspirators even talked of poisoning cans of beer at football games and arming radio-controlled airplanes with explosives and flying them into British cities.

The 13-month trial provided startling evidence not only of the chilling alienation within parts of Britain’s own Muslim community, but of what authorities believe are connections between al-Qaida and the British would-be bombers, who underwent paramilitary training in Pakistan.

In a revelation that triggered widespread concerns across Britain, it was learned that police knew of at least four meetings in 2004 between the plotters and the suicide bombers who carried out the July 2005 bombings in the London transport system, which killed 52 people.

While it was initially believed the transport bombers were unknown to authorities, evidence at the trial showed that police tailed one of the bombers, Mohamed Sidique Khan, as part of the current case well before the 2005 explosions.

The news prompted demands for a new inquiry into police handling of the transport bombing investigation. But police officials said they had no way of knowing at the time that Khan was a serious terrorism risk and had neither the resources nor the legal authority to open investigations without clear cause.

Prosecutors said the five defendants purchased 1,320 pounds of ammonium nitrate fertilizer, which can be used to manufacture explosives, and appeared to be casting about for a place to blow it up in retribution for Britain’s military presence in Afghanistan. Some of the defendants said their trips to training camps in Pakistan were in preparation for supporting Muslim fighters in the embattled Kashmir region on the India-Pakistan border.

Testimony from an American Muslim who was involved with the defendants in Pakistan revealed that two of the men claimed they were reporting to Abd al-Hadi al-Iraqi, whom they identified as the No. 3 representative of al-Qaida. U.S. authorities revealed last week that al-Hadi was taken into custody last year and is providing information about al-Qaida.

The Pakistani-born American, Mohammed Babar, testified under a grant of immunity.

The five Britons, Omar Khyam, 25, Anthony Garcia, 25, Jawad Akbar, 23, Waheed Mahmood, 35, and Salahuddin Amin, 32, were sentenced to life in prison for conspiring to cause explosions.