Terrorist Usman Khan, 28, was wrestled to the floor after he began stabbing at people on the stairs outside the main conference room at Fishmongers' Hall on Friday.

Khan killed Jack Merritt, 25, who worked for prisoner rehabilitation group Learning Together, and 23-year-old Cambridge University graduate Saskia Jones.

As Khan ran out to London Bridge to carry on his rampage, he was pursued by heroic former prisoners and staff.

When Khan saw the group chasing him, he is said to have shouted: "I'm not here for you. I'm here for the police. I have a bomb!"

Undeterred, several former prisoners - including murderer James Ford, 42, who was on day release - and staff chased the knife-wielding killer out of the building.

Extraordinary footage showed bystanders tackling the terrorist, who had two blades and was wearing what turned out to be a fake suicide vest.

Reformed ex-prisoner Marc Conway was one of the London Bridge heroes who bravely confronted Khan despite him claiming he had a bomb.

Moments before, Marc Conway was seen chatting with prison education specialists in Fishmongers' Hall when Khan began his murderous rampage.

One used a fire extinguisher on him and a Polish worker, said to be named Lukasz, is thought to be the hero who grabbed a 5ft whale tusk from inside the Fishmongers' Hall venue before chasing Khan with two others.

Tour guide Tom Gray, 24, who risked his own life with colleague Stevie Hurst, 32, to tackle Khan, stamped on the fiend's wrist to try to make him release one of the two large knives.

Tom said: "I was brought up on rugby and the rule is 'one in, all in'. I did what any Londoner would do."

A kitchen employee, named only as Mohammed, helped pin Khan down until cops arrived and shot the jihadist dead.

His boss said: "He held the guy down. He was on his break. He came back afterwards to work. He didn't say anything, he went back to work, washing dishes."

Toby Williamson, chief executive of Fishmongers' Hall, praised the bravery of staff who tried to stop the terrorist.

He told the BBC: "There was a scream, there was blood. People thought it was an exercise at first."

He recounted how two men, Lukasz and Andy, "used fire extinguishers, chairs and narwhal tusks ripped off the wall" to take the fight back to Khan.

He said: "They took a decision, one that enough was enough. They were determined it wasn't going to go on."

"They are two of the most humble people... but in the heat of the moment, people do extraordinary things. I am very proud to know them."

Khan is the first freed terrorist to launch an attack in this country.

Khan was freed to murder after appeal judges cut short his jail term over a previous plot.

He was one of three terrorists locked up in 2012 -all given indeterminate tariffs for "public protection".

A year later a three-strong appeal panel, led by Sir Brian Leveson, replaced the sentence with a fixed 16-year term, of which Khan should serve half in prison.

That meant he was freed on licence last December -without going before a parole board.

Khan was given "special permission" to attend the London conference on prisoners' rehab where he launched his attack.

He had been barred from the capital under his licence conditions.

But he was allowed by his probation officer to travel to the Learning Together conference at Fishmongers' Hall, north of London Bridge, on Friday.

He attended the morning session of the Cambridge University-run event before returning after lunch to launch his rampage.

No-one else is being sought over the attack.

West Midlands Police tonight said a man had been arrested on preparation of terrorist acts in Stoke in connection with a wider on-going review of licence condition following Friday's attack.

Mr Merritt's father David called his son a "beautiful spirit who always took the side of the underdog".

Writing on Twitter Mr Merritt said: "He was an exceptional young man, and I'm only finding out the half of it now he's gone."

A statement from Saskia's family read: "Saskia was a funny, kind, positive influence at the centre of many people's lives.

"She had a wonderful sense of mischievous fun and was generous to the point of always wanting to see the best in all people.

"She was intent on living life to the full and had a wonderful thirst for knowledge, enabling her to be the best she could be.

"Saskia had a great passion for providing invaluable support to victims of criminal injustice, which led her to the point of recently applying for the police graduate recruitment programme, wishing to specialise in victim support.

"This is an extremely painful time for the family. Saskia will leave a huge void in our lives and we would request that our privacy is fully respected."

London Bridge and Borough market were the scene of a terror attack in 2017, when eight victims were killed along with the three terrorists, who were also wearing fake suicide vests and armed with knives.

The latest attack comes weeks after the UK's terrorism threat level was downgraded.

The threat level was lowered on November 4 to "substantial" from "severe", meaning attacks were thought to be "likely" rather than "highly likely".