The party's deputy leader dragged Johnson in a scathing interview, comparing him to a "pound shop Donald Trump".
Boris faced a 90-day suspension after the partygate report found he had "deliberately misled" parliament during lockdown.
He won't have to go through with this suspension of course, following his resignation as a politician.
Reacting to the report, Angela said: "I think the Privileges Committee report is pretty damning.
"It's serious. Boris Johnson is not only a law breaker but a liar, and he is not fit for public office.
"He's disgraced himself and continues to act like some pound shop Doland Trump in the way in which he tries to discredit anybody who criticises his actions."
She added: "A decent public servant would have done the honourable thing and would have had a little bit of humility, and would have apologised."
Johnson has since said he fell victim to a "witch hunt" with the partygate report.
Rayner responded: "I think it's a load of rubbish and he knows it, and that's why he didn't challenge it.
"You see, that's why he's resigned because he knows he won't win that by-election and because he knows the public could see through this act, this clown act that he puts on.
"It's pretty obvious that that report is very damning. It's what happened. And he's disgraced himself and he should apologise to the British people.
"And Rishi Sunak shouldn't have propped him up for as long as he has."
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