Clad in mud-smeared combat fatigues, the young Muslim men trained in picturesque British farmland, hurling imaginary grenades, wielding sticks as mock rifles and chopping watermelons in simulated beheadings.
Tourists and others who stumbled across this sight _ described by eyewitnesses in a London courtroom over recent weeks _ struggled to stifle laughter.
But a 4-year inquiry, which ended Tuesday with the convictions of seven men, has exposed a network of alleged British terrorism training camps with a serious intent to prepare recruits for mass-murder.
Security officials believe hundreds of men _ including a gang that made a failed attempt to bomb London's transit network _ passed through camps across the English countryside.
Investigators say their discovery exposes a worrying development at the heart of British homegrown terrorism: training camps once thought to be exclusive to northern Pakistan or Afghanistan are being held in sleepy rural England.
Two ringleaders will be sentenced next month on charges of running the camps and inciting participants to murder. Their convictions, and five others, can be reported for the first time Tuesday after a judge lifted restrictions banning publication of details of a four-month trial.
Prosecutors told a trial that the men set up camps in idyllic spots across England to train in a range of paramilitary skills.
National parks in the Lake District, in northern England, and the New Forest, in southern England, and quiet corners of the southern counties of Berkshire, Kent and East Sussex were all used for training _ including a former school.
Officials fear the case shows British citizens can now be radicalized, trained and funded to carry out terror attacks _ without ever leaving the country.
The British camps, which gave instruction to around 10 men at a time, also offer a glimpse of the training centers British-based radicals hoped to open in Oregon, in the United States, before authorities halted their plans.
"People have got to be alert to the fact that right in the middle of our society these things are going on," said Patrick Mercer, an opposition Conservative lawmaker and ex-intelligence officer.
The development may help explain why Jonathan Evans _ head of domestic intelligence agency MI5 _ says Britain faces an ever growing number of potential terrorists within its borders, which he last year put at around 2,000.
Secretly filmed video from the camps shows recruits marching with backpacks _ used by London's transit network attackers to carry their suicide bombs _ and carrying out weapons drills favored by insurgents in Iraq and the Taliban.
An undercover police officer, codenamed "Dawood," infiltrated one group and captured cell phone video of the training. One clip shows trainees rehearsing a beheading with a watermelon.
While security officials say the techniques often appear comical _ in one video, two recruits fall into a river _ they insist the training provides crucial psychological cohesion for would-be radicals.
"What's important is bonding people together, just like traditional team building exercises carried out by businesses," said a government security official, who demanded anonymity to discuss the inquiry.
A gang of North African men who made a failed attempt to bomb London's transit network on July 21, 2005, two weeks after the July 7 subway and bus strikes that killed 52 commuters, met and were trained at one of camps, the official said.
"For the July 7 group it was whitewater rafting, for the July 21 group it was meeting at these camps which was the key factor in bringing them together as a cell," the official said.
Officials said the ringleaders were two notorious London-based preachers: Atilla Ahmet, who once told a CNN interview he was "the number one al-Qaida in Europe," and Mohammed Hamid, who gave himself the nickname "Osama bin London."
Ahmet is a longtime aide of radical preacher Abu Hamza al-Masri _ an Egyptian who the U.S. is attempting to extradite over plans to set up terror camps in Oregon.
Hamid, originally from Tanzania, hand-picked recruits from mainstream mosques, inviting them for radical meetings at his home and then selecting a smaller number to attend the camps.
The two men will be sentenced at a court hearing next month. Five accomplices were scheduled to be sentenced on Tuesday.
Somalian Kader Ahmed, West Indies-born Mohammed Al-Figari, Jamaican Kibley da Costa and Londoners Mohammed Kyriacou and Yassin Mutegombwa were all convicted on charges of attending terrorist training.
Ahmed told his trial that scores of tourists saw a training camp in Cumbria, northern England, in 2004. "They were kind of shocked at the big beards but we spoke to them just to break the ice," he said.
Farmer Bruce Rowland, who rented a field to the men, told police he originally jokingly called the group "my Taliban" _ before becoming concerned. At a paintballing center north of London, a female member of staff told officers how customers had laughed at the men.
Hamid, prosecutors said, was candid about his hope that the recruits could dwarf the scale of the 2005 London bombings. He hoped they would carry out six or seven major attacks before London hosts the 2012 Olympics, prosecutors claimed.
"Fifty-two. That's not even breakfast for me," Hamid was recorded as saying on a bug installed in his home, referring to the number killed in 2005 blasts.
One of Hamid's recruits was Muktar Said Ibrahim, who led the July 21 gang. The two had been arrested together in central London in 2004 as they handed out extremist leaflets.
A year later, Ibrahim and three accomplices attempted to set off bombs on three subway trains and a bus. Their devices failed, though police said tests proved the bombs were viable.
Dozens trained at Hamid's camps were hoping to carry out attacks, said a senior police official, who demanded anonymity to discuss counterterrorism work. "There was repeated talk of finding and killing nonbelievers," he said.
But police said the camps were also used to prepare unfit British Muslims for training, or combat, overseas. "There are repeated instances of people, particularly from the West, being sent home from training camps overseas for being unfit," the police official said.