London Bridge hero John Crilly used fire extinguisher try to ‘to short-circuit terrorist's suicide vest’

John Crilly left, with his friend and mentor Jack Merritt

A reformed ex-prisoner who tackled the London Bridge attacker with a fire extinguisher has revealed he was trying to short-circuit the terrorist’s “suicide vest”.

John Crilly, 48, chased Usman Khan after watching him stab his friend and mentor Jack Merritt, 25, to death during an event at Fishmonger’s Hall in the City of London.

Snatching the extinguisher from the wall he blasted Khan with the foam, pushing him back and potentially saving many lives.

But his real aim had been to disable what appeared to be an explosive belt worn by the knifeman, he told The Mirror.

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Speaking for the first time of the moment he seized his makeshift weapon, he said: “At first, I thought throw that at him, then I thought I could spray it and soak the belt, maybe short-circuit the belt."

Khan attacked five people including Mr Merritt and Saskia Jones, 23, armed with two kitchen knives and an apparent suicide vest, before he was tackled by Mr Crilly and several others on London Bridge.

The convicted terrorist was then shot dead by police at point-blank range, but it later emerged the vest had been a fake.

Jack Merritt and Saskia Jones both died in the London Bridge terrorist attack (AFP via Getty Images)

Mr Crilly became an overnight hero after footage of his attempts to subdue Khan were shared across social media.

It soon transpired he was a former prisoner and participant of the Learning Together inmate reform programme for which Mr Merrit was a course coordinator.

The pair met while Mr Crilly was serving a 13-year jail term for manslaughter at HMP Grendon, Bucks, and the 25-year-old became his prison mentor.

He told The Mirror the Cambridge graduate had helped him turn his life around and was the "best guy I ever met".

The 48-year-old studied for an Open University law degree while in prison and Mr Merritt attended his graduation this year.

Mr Merrit’s friends and colleagues hailed Mr Crilly’s bravery following the shocking events of November 29.

One Facebook user wrote: “I honestly think your friend would be proud of you John Crilly for your actions, so many people could have died if it wasn’t for your quick thinking!! Be proud of yourself.”