RICHARD Ottaway MP has said the guilty plea of a police officer involved in the 'plebgate' affair is a "very black day for the Met".
PC Keith Wallis, 53, has admitted falsely claiming to have witnessed a row between then-cabinet minister Andrew Mitchell and police in September 2012.
He pleaded guilty to misconduct in public office and has offered to resign.
Asked by the BBC whether the affair had become a "major crisis" for the Met, Croydon South MP Sir Richard called it a "very black day".
"We now have firm evidence that a police officer has lied to bring down a cabinet officer and a huge injustice has been done," he said.
"The Met has got a lot to answer for at the moment."
Mr Mitchell, then chief whip, was stopped from cycling through Downing Street's main gates by another officer, Tony Rowland.
He admitted swearing during the incident but not directly at the police or using the word "pleb".
It was labelled by the media as "plebgate" and led to Mr Mitchell stepping down from his cabinet position.
PC Wallis later sent an email to his local MP John Randall wrongly stating he had witnessed the argument.
He pleaded guilty to the charges when appearing at the Old Bailey today (Friday).
Met Commissioner Sir Bernard Hogan-Howe, who had previously stated his support for the officers involved, has apologised to Mr Mitchell.
Speaking on BBC Radio 4's The World at One programme, Mr Ottaway was asked whether the affair called into question the Commissioner's position.
He replied: "Mr Hogan-Howe said right at the outset that he had 100 per cent confidence in his officers and I think he would be the first to admit now that was a misjudgement.
"It's too early to judge at the moment. Obviously people will call for his resignation but I personally don't want to make a judgement on that at the moment.
"I actually think he's a pretty good Metropolitan Commissioner but if, at the end of this, we find ourselves facing the situation whereby he has made a serious misjudgement then no doubt he will be thinking very hard about his future."
Mr Ottaway added: "That [his public support of the officers] was the most damaging point in this.
"It's something he didn't have to say. He could have said 'There have been allegations against my officers, I'm investigating it and I will serve in the interests of the people of London'.
"That would have been much better than what he actually did say."
