Media playback is unsupported on your device Media caption John Crilly describes how the attack unfolded, and what he did next

A reformed ex-prisoner who fought the London Bridge knife attacker with a fire extinguisher has said he was prepared to die to protect others.

John Crilly, who was jailed for murder after a burglary went wrong, said he tackled Usman Khan while believing he was wearing a live suicide belt.

"I was screaming at him to blow it. I was prepared to lose my life."

As he and others fought Khan on the street, he shouted at police to shoot the attacker.

In his first broadcast interview since the attack, Crilly, 48, told of the moment armed police confronted the knifeman on London Bridge.

He said: "It seemed like ages before they shot him. It wasn't all gung-ho and trigger happy, they proper took their time, to the point where I did scream 'shoot him'."

Khan, convicted of terrorist offences in 2012, killed two people - Cambridge University graduates Jack Merritt and Saskia Jones - and wounded three others when he launched a knife attack on 29 November at 13:58 GMT during a prisoner rehabilitation conference at Fishmongers' Hall.

Image caption John Crilly (left) with Jack Merritt, the Cambridge University graduate killed in the London Bridge terror attack

Crilly had been attending the Learning Together conference and remembers hearing a "very high-pitched girl's scream" when he knew something was wrong.

He went downstairs to find Miss Jones, 23, lying wounded, before he saw Khan in the corridor, armed with two knives.

After shouting at Khan, asking him what he was doing, Crilly remembers his chilling reply: "He says something like 'kill everyone' or 'kill you', something about killing people."

When asked if he thought Khan was targeting specific people, he said: "It seemed like everyone there was fair game.

"I just assume now that he just saw it as a big target. A room full of establishment people - judges, probation, police, security."

Image copyright Met Police Image caption Jack Merritt and Saskia Jones were killed during a conference to rehabilitate offenders

Staff and participants of the conference attacked Khan with whatever they could find.

Crilly fought him first with a wooden lectern and then a fire extinguisher, all the while believing he was wearing a live suicide belt.

He said he acted on "instinct" and "was screaming at [Khan] to blow it [the belt]... calling his bluff."

But he said Khan told him he was "waiting for the police" to arrive before detonating the belt, which police later found to be fake.

"I was prepared to probably lose my life", he said.

Two men used a pole and a whale tusk ripped from the venue's wall to fight off Khan and force him out of the building.

Crilly and others used their makeshift weapons to pursue Khan onto the street on London Bridge.

In video footage, he is seen using the spray from a fire extinguisher to blind Khan, while another man held him back with the whale tusk.

He said: "The spray distracted him if you watch the footage. And the guy with the tusk has been able to give him a prod which has unbalanced him."

Other bystanders intervened to pin Khan down before police shot him dead at 14:03.

Media playback is unsupported on your device Media caption Video footage shows moment London Bridge attacker was apprehended

Crilly was close friends with Mr Merritt, 25, the co-ordinator of the Learning Together programme who he says changed his life.

He described Mr Merritt as "easy to talk to" and who "made you feel comfortable, even important".

"He actually listened and you could tell he was really genuinely interested."

The people that intervened to try and halt Khan's attack have been widely praised as "amazing heroes".

Asked if he considers himself a hero, Crilly said: "No. Jack gave up his life, he would be my hero."

Image copyright MET POLICE Image caption Jack Merritt was "easy to talk to... and made you feel comfortable"

Crilly was given a life sentence for murder and robbery in 2005 after he and his associate David Flynn broke into the home of 71-year-old man in Manchester.

The pensioner died after being punched in the face by Flynn.

Crilly was convicted under the joint enterprise law - which can apply to all crimes, but has recently been used to convict defendants in gang-related cases even if they did not strike the fatal blow, but could have foreseen that their associates might inflict serious harm or kill.

It was known as the "foresight" test and some believed it set the prosecutorial bar too low, allowing bit-part players or those on the periphery to be convicted of murder and given life sentences.

However, in February 2016, the Supreme Court ruled the law had been interpreted wrongly for more than 30 years.

The foresight test went and a higher test was introduced.

To be guilty of murder, the prosecution had to prove that the defendant intended to assist or encourage the crime.

However, most of those who wanted to appeal against their convictions were out of time, and the Supreme Court said they had to show they would suffer a "substantial injustice" if they were not allowed to appeal out of time.

While in prison, Crilly completed a law degree.

When he heard about the overturning of the joint enterprise law in 2016, he believed it would apply to his case.

After a successful appeal against his murder conviction, Crilly pleaded guilty to manslaughter, becoming the first person since 2016 to have a joint enterprise murder conviction quashed.

He was released on licence last year after serving 13 years in prison. No-one else has successfully appealed such a conviction since 2016.

Image caption Crilly pleaded guilty to manslaughter after his murder conviction was overturned

Speaking at the time, the victim's family said the "incident had a devastating effect on the family who took a number of years to come to terms with their father's death".

They said it was "sickening" to hear of his early release from prison "for his part in the murder of our father".

"We wish him well but also wish that our father were alive and free to live his life."

The campaign group Joint Enterprise Not Guilty by Association (Jengba), which helped bring about the law change, works with people who have been convicted of murder or manslaughter under joint enterprise.

Co-founder Jan Cunliffe said the group is always mindful of the victims of crime. She claims that although the law change is welcome, the introduction of a "substantial injustice" test for retrospective cases has made it harder for people to appeal against their convictions.

She said although Crilly did commit crimes when he was younger, "everybody should have the opportunity to turn their life around".

"If John hadn't been there and been kept in prison for life, he wouldn't have been there to save lives that day."

In the new year, the group will campaign for the abolition of life sentences for children convicted of murder under the joint enterprise law.