But The Independent has uncovered a different picture of Tanweer, one in which the Aldgate bomber is a highly focussed, motivated and independent jihadist, who spent time - without Khan - at a terrorist training camp in Pakistan run by a group linked to the kidnap and murder of an American journalist. He also helped lead a gang in the Beeston district of Leeds that introduced radical Islam to Asian youths and engaged in battles with whites.

The training camp Tanweer visited in Pakistan was run by Harkat-ul-Mujahedeen (the "Movement for Holy Warriors"), a group that had been involved in the kidnap and beheading of Wall Street Journal reporter Daniel Pearl in 2002 and which trains fighters operating alongside the Taliban in Afghanistan and Pakistan.

One of Tanweer's former associates said the bomber had received lessons in handling arms and explosives at the camp in Mansehra, a remote area near the Kashmir border, in December and January. This is corroborated by sources in Pakistan, one of whom claims that he had two stints at the camp. Tanweer is known to have visited Pakistan between last November and February with Khan. But Pakistani sources who place Tanweer at Mansehra cannot recall him being accompanied by Khan or any other British Muslim.

The man who organised the kidnapping of Pearl, Omar Saeed Sheikh, was another British-born Muslim who had joined Harkat. Security sources in Britain say they have not yet found any link between Tanweer and Sheikh.

Tanweer, travelling on passport number 453897014, and Khan, number 04069095, arrived in Karachi via Istanbul on Turkish Airline flight TK-1056 on 19 November last year. They left for Lahore by train a week later before moving on to Faisalabad where, according to Pakistani security sources, their trail disappeared before they surfaced again in Britain on 8 February.

A month before he showed up at Mansehra, Tanweer is known to have been in Chak 477, 28 miles from Faisalabad, where he visited his father's family. His time there provides more evidence of his obsessive pursuit of jihad.

Young men usually play cricket in Chak's main street but Tanweer - a talented batsman - had no interest. Instead, he wanted to pursue several of the groups who were expounding the jihadi cause. According to Tahir Pervaiz, his uncle, the family was so concerned that attempts were made to keep him inside the house. "Osama bin Laden was Shahzad's idol and he used to discuss the man with his cousins and friends in the village," said Mr Pervaiz.

Tanweer seems to have spent time with Khan at Chak. Khan made a number of trips from Rawalpindi, where he was staying at the the house of an uncle, according to Mr Pervaiz.

The link between the two men dates back to the 1980s. In recent years their friendship had developed into membership of a 15-strong group of Asian youths known as "The Mullah Crew".

The group's meeting points included a local Iqra Islamic bookshop, which was raided by police after the bombings, and a gym beneath Beeston's Hardy Street mosque.

Their radicalism was so blatant that the gym became known as the "al-Qa'ida gym", according to Tanweer's associates.

But many were prepared to overlook this because the leaders of the Mullah Crew were known for energising many disenchanted Muslim boys whose heroin abuse was giving the Asian community a bad name.

Tanweer seems to have been integral to this process. "He and the Mullah Crew cleared up the area," said a source. "Lads would be taken by the group and put through cold turkey by locking them in a room for five days."

The Mullah Crew's emphasis was on strengthening the young Asians physically, often through outdoor activities like paintballing, climbing in the North Yorkshire Moors and canoeing in North Wales. Tanweer was more committed than most and he is particularly remembered for a paintballing trip in which he proved superb with the gun. "He was approaching it like a proper soldier," said the source.

Islam was also a part of the Mullah Crew's creed of clean living. "To be invited on one of these outings you had to be a part of their religious set," said another source. "They would not take lads who had become too 'Westernised' for their liking."

Another Mullah Crew trip saw an ill-equipped group go half-way up Mont Blanc before they were forced to head back. "Going without the proper equipment made it seem as if they were testing their strength for the jihad; testing their faith," said the source.

It appears that Tanweer took every aspect of life seriously, from cricket (he batted for Shaan B in the Quaid E Azam Yorkshire league) to snooker (he rejected the usual, smoke-filled clubs in favour of the Northern Club in Leeds, which has its own coach).

When it came to guarding what he perceived to be his territory, his independent spirit sometimes led to violence. The windows of his family's chip shop were smashed after fights broke out between white and Asian youths in Beeston. Tanweer seems to have planned to get his own back. "He was part of a group which planned to go to the white part of Beeston and get some revenge," said a source.

The feud resulted in a fight that led to the death of Tyrone Clarke, 16, at the hands of a gang of Asian youths in April 2004. Tanweer had no involvement in the murder but did receive a caution for a public order offence arising out of the gang battles.

When it came to organising the bombings, Tanweer was determined to take on tasks. He booked the Nissan Micra rental car that would take him, Khan and Hasib Hussain to Luton railway station on 7 July.

At least one family member has suggested there were hints of what he planned in his demeanour. "[The family] were watching a documentary on Muslims in Britain [in May]," she said. "Shahzad was convinced there would be a battle between Muslims and the West. [He said] 'You'd better get out of here. Everyone's going to hate you'."