One of the alleged 21 July bombers came to the notice of police three times before the attacks, a court has heard.
The surveillance photos were show to the jury
Muktar Said Ibrahim was photographed by surveillance officers alongside four of his five co-defendants at a camping trip in the lake district in May 2004.
Soon afterwards he was arrested for distributing "Islamic literature" in London's Oxford Street, and was later questioned by officers at Heathrow.
All six men deny conspiracy to murder and conspiracy to cause explosions.
Woolwich Crown Court was told that Mr Ibrahim was part of a group alongside Hussein Osman, Yassin Omar, Ramzi Mohammed and Adel Yahya camping in Cumbria 15 months before the alleged suicide bomb attacks.
Mr Yahya is accused of helping to plan the alleged attacks while the others and Manfo Asiedu are all said to have set out on 21 July 2005 to bomb London's transport network.
Photographs showed the group as they packed up and prepared to leave a campsite on a farm in the Elterwater area of the Lake District.
The jury heard several men - including Mr Osman, Mr Yahya, Mr Mohammed and Mr Omar - appeared to line up at one stage and engage in Islamic prayer.
Two Metropolitan Police officers were the first witnesses to begin giving evidence at the trial.
Muktar Said Ibrahim, 28, from Stoke Newington, north London
Ramzi Mohammed, 25, from North Kensington, west London
Yassin Omar, 26, from New Southgate, north London
Hussein Osman, 28, of no fixed address
Manfo Kwaku Asiedu, 33, of no fixed address
Adel Yahya, 24, of High Road, Tottenham, north London
One officer said a group also seemed to be taking part in some kind of organised running activity while wearing rucksacks.
"They did not appear to be running randomly," he said.
"It appeared as though there were a series of men in a line running up and down."
A few months later, Ibrahim was arrested outside Debenhams on Oxford Street in London for distributing "Islamic literature".
Soon after, in December 2004, he was questioned by Special Branch officers at London's Heathrow airport, while due to travel to Islamabad in Pakistan, the court heard.
Det Con Louis Chryssaphes said Ibrahim was carrying more than £2,000 in cash, plus a brand new video camera and video phone. He was also had a sleeping bag, cold weather clothes and anti-malarial tablets, the jury heard.
Mr Ibrahim and two companions said they were to attend a wedding and were allowed to travel to Pakistan the following day. The prosecution claimed the purpose of trip was "to take part in jihad or to train for it".
The jury also heard an imam tell the court how Mr Omar confronted him in a mosque after he had preached that suicide bombing was wrong.
Sayed Bukhari said Mr Omar challenged him in a "stressful" and "argumentative" manner after Mr Bukhari condemned a suicide attack in Palestine in 2005 before a congregation in Finchley, north London.
Mr Bukhari said Mr Omar told him: "Don't mislead the people."
A friend of Mr Omar and Mr Yahya told the jury the men had become increasingly devout after attending London's Finsbury Park Mosque to hear prayers by the cleric Abu Hamza al-Masri.
Steven Bentley said he had converted to Islam himself after encouragement by Mr Omar, who seemed to support the Taleban's regime in Afghanistan.
Mr Omar also apparently did not believe the 11 September 2001 attacks on the US were the work of al-Qaeda leader Osama Bin Laden.
Mr Bentley told the court: "He did say he didn't think it had been done by Osama Bin Laden. He said Abu Hamza had said that it wasn't, and Abu Hamza knew Osama Bin Laden."
The trial continues.