MIKE Amesbury was arguing with a constituent about the winter fuel allowance and the closure of a bridge moments before punching him, a witness has claimed.
The Labour MP, 55, was caught on camera flooring a man with a left hook before appearing to unleash a number of punches in the early hours of Saturday.
Amesbury has since been suspended and quizzed by cops, as pressure grows for him to stand down - and he's been warned he faces prison.
Now, the man he punched has since been identified as Paul Fellows, 42, reports
A witness has claimed that Fellows had been talking to Amesbury about plans to close a nearby bridge for 33 days between January and March for engineering works.
Amesbury had previously described the closure of the Sutton Weaver Swing Bridge, which carries the A56 over the River Weaver Navigation, as “unacceptable”.
The source added that the conversation also touched on the winter fuel allowance before it grew “heated” on both sides.
However, they claimed there had been no physical provocation until the punch.
Amesbury, MP for Runcorn & Helsby in Cheshire, was involved in the scuffle in Frodsham, Cheshire, within his own Runcorn and Helsby constituency.
The Labour MP released a statement prior to the damning CCTV evidence emerging saying he had "felt threatened" during the 2.15am altercation.
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As fresh details continue to emerge, one woman whose sister was waiting for a taxi at the same time, claimed Mr Amesbury was "just drunk and beat someone up".
She told The Times: "He is trying to get out of it now. He was trying to beat him to a pulp.
"My sister tried to intervene and pull him off. You have seen the video of how drunk he was. She was waiting for a taxi and so was the man."
It's believed that the MP was drinking at local pubs before the attack.
Hours before the brawl, he had attended a meeting with the local police commissioner in which he said he was "listening to residents concerns and ideas for policing and community safety".
Initial mobile phone video showed the MP shouting "you'll never threaten me again" as the man lay on the ground next to a taxi rank.
When someone in the background points out Amesbury is the local MP, he says: “Yes I am. You won’t threaten the MP ever again, will you?”
However, CCTV footage then emerged showing him seemingly throwing the first punch.
He appears in animated fashion before letting loose a strike to the man's head.
The MP then continues to swing up to six more strikes at the man while he's sat on the floor - though it's unclear how many connect.
Suspending the Labour whip in the Commons, a party spokesman said: "Mike Amesbury MP has been assisting Cheshire Police with their inquiries following an incident on Friday night.
"As these inquiries are now ongoing, the Labour Party has administratively suspended Mr Amesbury's membership of the Labour Party pending an investigation."
Sir Keir Starmer said the incident was “shocking” and defended Labour’s decision to suspend him.
However, friend and former Labour adviser Matthew Torbitt has claimed the former member of Sir Keir Starmer's Shadow Cabinet was subjected to a "lengthy wind up".
He said Amesbury had also suffered "personal attacks" before throwing the drunken punch.
Mr Torbitt told GB News: "I cannot put into words how out of character this is… he's gentle, he's very kind, he's very laid back...
“I won't divulge private conversations, from what I can gather from other people there was a sustained wind up, a personal attack that evening by said individual in the videos.
"However, no one can make any excuse for the reaction it has provoked."
But Tory leadership hopeful Robert Jenrick has said Amesbury should not be an MP following the brawl.
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Reform UK, which came second in Amesbury's Runcorn seat, has urged the Labour politician to trigger a by-election immediately.
Cheshire Police confirmed that a 55-year-old man had been voluntarily interviewed under caution about the incident and had been released pending further inquiries.