The murderers who hacked British soldier Lee Rigby to death were both Londoners from devout Christian Nigerian families who became self-styled "soldiers of Islam" intent on martyrdom.

Michael Adebolajo and Michael Adebowale butchered Rigby in order to generate maximum media coverage, be killed by armed police and "gain a place in paradise", judge Nigel Sweeney said Wednesday as he sent them to prison.

Adebolajo, 29, who was jailed for life, had been an ordinary, articulate London youth who ended up being monitored by the British security services for his growing radicalism.

His 22-year-old accomplice, imprisoned for a minimum 45 years, was bullied at school, suffered mental health problems and drifted into gang life before converting.

Minutes after attempting to behead Rigby in broad daylight on May 22 last year, Adebolajo told horrified onlookers he was "forced by the Koran" to "fight them as they fight us. An eye for a eye and a tooth for a tooth".

Mobile phone footage taken by an eyewitness of Adebolajo ranting, his hands soaked in Rigby's blood, stunned Britain.

A married father of six, Adebolajo was known to British security services.

He was arrested in Kenya in 2010, close to the border with Somalia -- home to the Shebab Islamist militants.

He told a Kenyan court he had wanted to go and live in Somalia under sharia, or Islamic law.

Childhood friends remembered Adebolajo as a classroom joker with the same interests as any other British teenager -- football, chasing girls, playing video games and listening to rap music.

- 'Very peaceful chap' -

Detectives have tried to piece together how he turned from a church-going boy into a Muslim radical.

He converted to Islam in 2003 while studying politics at Greenwich University in southeast London and adopted the name Mujahid.

Adebolajo appeared at several public events with members of Al-Muhajiroun, a group founded by banned Islamist preacher Omar Bakri and proscribed under anti-terror laws.

Anjem Choudary, the group's former leader in Britain, told AFP: "He used to attend some of our activities over the years. Very peaceful chap actually, not violent at all, very pleasant."

Adebolajo was "a normal guy", Choudary said, adding: "He used to propagate Islam, (he was) concerned about foreign policy.

"He attended some of the activities, demonstrations, processions, talks.

"We lost any kind of contact with him about three years ago."

In 2006 Adebolajo joined a protest outside the Old Bailey -- the same London court where he himself was convicted -- in support of a Muslim accused of calling for the killing of British soldiers.

In a scuffle, he was convicted of assaulting a police officer and received a 51-day jail term.

He and 22-year-old Adebowale owned speeches and books about religious war and martyrdom.

After returning from Kenya in 2010, Adebolajo was approached several times by MI5, Britain's domestic security agency and, according to his family, reportedly turned down their offer to become a spy and grew frustrated at being "pestered" by them.

Adebolajo's sixth child was born just four days before the brutal attack on Rigby.

- Traumatised by fatal attack -

Adebowale, whose father, a Nigerian High Commission official, split from his probation officer mother when he was a young boy, was haunted by a 2008 knife attack in which drug-crazed assailants wounded him and killed his best friend.

He suffers mental health problems and told prison psychologists he would hear his attackers' voices in his head for 10 minutes in the morning.

His went missing from home several times and his mother thought he was coming under the influence of a local gang and getting involved with drugs.

She asked her friend Richard Taylor to mentor him. In 2000, Taylor's son Damilola was murdered aged 10 in London in a notorious killing that shocked Britain.

"He was a young, loving boy, quiet," Taylor said of Adebowale.

Taylor said he last spoke to Adebowale around two months before the killing.

"He said, 'I'm cool, I've changed, I've become a Muslim.'"

Adebowale has never explained his actions, choosing not to testify in court.

"Nothing I could have said would have changed him," Taylor said, adding: "They don't deserve to live."