Three of the four men behind the UK's first suicide bombings on 7 July last year were British and the other a Jamaican-born British resident. Below are profiles of the young men who went on to kill 52 people and injure hundreds.
MOHAMMAD SIDIQUE KHAN, 30, FROM DEWSBURY
Mohammad Sidique Khan had lived in the Beeston area of Leeds, then moved to Lees Holm in Dewsbury.
He was married to Hasina, and the couple had one young daughter.
Mohammad Sidique Khan was respected by pupils and parents
The 30-year-old had been a teaching assistant at Hillside Primary School in Leeds since 2002.
Parents at the school told the BBC the teaching assistant had been highly regarded by children and parents.
"He was a good man, quiet," said one.
During its last Ofsted inspection in 2002, the school's learning assistants had been singled out for special praise in dealing with a transient pupil population from a socially deprived area.
Khan told the Times Educational Supplement at the time that "a lot of [the pupils] have said this is the best school they have been to".
Mohammad Sidique Khan was born in Leeds in 1974
Last November a BBC Radio 4 documentary found Khan spent most of his life as a westernised youth calling himself by the nickname "Sid" and did not talk about religion.
As a teenager, he shook off his Pakistani-Muslim identity, claim friends, and chose to present himself as an exclusively westernised young man going by the nickname "Sid".
A friend from school days, Rob Cardiss, said: "He used to hang around with white lads playing football.
"Some of the other Pakistani guys used to talk about Muslim suffering around the world but with Sidique you'd never really know what religion he was from."
BBC reporter Nasreen Suleaman talked to Khan's former friends, who said he later became radicalised when he joined a tight-knit group of young Muslim men from Dewsbury, Leeds and Huddersfield.
Khan was known to the MI5 but officers assigned to investigate him were diverted to another operation.
BBC News learned the security services had been so concerned about him they had planned to put him under a higher level of investigation. He was also known to the police for suspected petty fraud.
In November 2004, the teaching assistant travelled to the Pakistani city of Karachi along with fellow bomber Shehzad Tanweer.
It is not clear what the men did during the three months they spent there,
but Pakistani records show the pair left on the same flight in early February.
On 7 July Mohammad Sidique Khan detonated enough explosives on a Circle Line train to kill seven people.
Documents belonging to him were found near the Edgware Road blast.
His family suggested in a statement that he had been "brainwashed".
In September 2005, a video featuring Khan was shown on the Arab TV network al-Jazeera, in which he was shown criticising British foreign policy and saying he was a soldier fighting a war.
But friends of Khan believed the message had been recorded some weeks or months before the bombings.
Experts in counter-terrorism told the BBC at the time of its release that the video did not prove the attacks were directly ordered by the al-Qaeda leadership.
HASIB MIR HUSSAIN, 18, FROM LEEDS
Teenager Hasib Hussain had been known as a tearaway during his early teens.
Hasib Hussain became devoutly religious after a trip to Pakistan
In the aftermath of the London bombings, newspapers reported how he would start fights with fellow pupils at the Matthew Murray Secondary school in Leeds.
He left school in July 2003 with seven GCSEs.
Around this time, he was sent to Pakistan to visit relatives. He also went on the Hajj pilgrimage to Mecca, grew a beard and began to wear robes.
Despite becoming devoutly religious, he was arrested for shoplifting during 2004.
Neighbours said the 18-year-old had lived all his life in Colonso Mount, in the Holbeck area of Leeds. One neighbour described the family as "very nice people".
He said: "We all knew them but I
wouldn't say I knew them well. They were just a very nice family."
Hasib Hussain was born in Leeds in September 1986
Hasib Hussain had told his family he was going on a trip to London to visit friends.
But when he failed to return on Thursday, his parents reported him as missing to police.
He had in fact boarded the No 30 bus in London armed with enough explosives to rip the double-decker apart, killing 13 people.
His driving licence and cash cards were found in the mangled wreckage of the bus.
His family later said they were "devastated" by what had happened.
In a statement they described Hussain as "a loving and normal young man who gave us no concern".
"We are having difficulty taking this in," they said.
"Our thoughts are with all the bereaved families and we have to live ourselves with the loss of our son in these difficult circumstances.
"We had no knowledge of his activities and, had we done we would have done everything in our power to stop him. "
SHEHZAD TANWEER, 22, FROM LEEDS
Shehzad Tanweer, 22, was born in Bradford but lived most of his life in the Beeston area of Leeds - little over half a mile from his friend, Hasib Hussain.
He was a sports science graduate whose interests included cricket and ju-jitsu.
Shehzad Tanweer's uncle said his nephew was 'proud to be British'
In 2004, he was arrested for disorderly conduct and cautioned.
In November the same year he travelled to the Pakistani city of Karachi along with Mohammad Sidique Khan.
Reports that he visited the eastern cities of Lahore and Faisalabad have not been confirmed, but his family has said he attended an Islamic school, or madrassa, during this visit.
Pakistani officials say he was also briefly in the country on at least one other occasion, possibly at the end of 2003.
Newspapers quoted friends who said Tanweer was quiet and very religious but did not express an interest in politics.
Shehzad Tanweer was born in Bradford and brought up in Leeds
Tanweer's uncle, Bashir Ahmed, 65, said the family was "shattered" by the revelation that he appeared to have been involved in the bombings.
"He was proud to be British," he said. "He had everything to live for. His parents were loving and supportive.
"He was a very kind and calm person. He was respected by everyone."
Neighbours described the graduate, who studied at Leeds Metropolitan University, as a "good Muslim". Others said he was a "nice lad" who could "get on with anyone".
Yet Shehzad Tanweer detonated a bomb on a Circle Line train between Aldgate and Liverpool Street stations which killed seven people, including himself, and injured over 100 more.
The remains of Tanweer were buried near his ancestral town of Samundari in Punjab province, Pakistan, in October 2005.
GERMAINE LINDSAY, 19, FROM AYLESBURY, BUCKINGHAMSHIRE
Lindsay converted to Islam and changed his name
The fourth suicide bomber was identified as Jamaican-born British resident Germaine Lindsay, who lived in Aylesbury.
Lindsay spent his teenage years in Huddersfield, West Yorkshire, like his fellow bombers.
He moved there in 1999 with his mother and sister, and moved away in 2003.
During this time he changed his name to Jamal Lindsay and began attending after-school classes to improve his knowledge of Islam.
Lindsay was married to Samantha Lewthwaite, with whom he had a young boy.
Since his death, Ms Lewthwaite has given birth to a daughter by Lindsay.
In a statement made just after Lindsay's death, Ms Lewthwaite said she "never predicted or imagined that he was involved in such horrific activities".
"He was a loving husband and father," she said.
"My whole world has fallen apart and my thoughts are with the families of the victims of this incomprehensible devastation."
In a subsequent interview with the Sun newspaper, in September 2005, she condemned his "abhorrent" Tube attack.
She said she wanted to remember the man she loved, but added: "The day will come when I'll have to tell [our children] what he did."
Trips to radical mosques had "poisoned" the "innocent, naive and simple" 19-year-old's mind, Ms Lewthwaite said.
A statement issued by his relatives Andrew, 49, Sabrina, 28, Allan, 25, and Carly, 21 said Lindsay "had a kind, caring and calming presence about him".
"He was a good and loving husband and a brilliant father, who showed absolutely no sign of doing this atrocious crime.
"We as a family had no idea of his plans and are as horrified as the rest of the world."