A police officer involved in the Plebgate scandal has pleaded guilty in court to misconduct in public office.
PC Keith Wallis has admitted sending an email in which he lied when he said he had witnessed an incident between the former Chief Whip Andrew Mitchell and a police officer at the gates of Downing Street in 2012.
During the incident, Mr Mitchell was alleged to have called the officer a "****ing pleb" after they became embroiled in an argument when the PC refused to let him cycle through the main gates.
Details of the row appeared in national newspapers and Mr Mitchell was forced to resign.
The Tory MP has always maintained that he never used the word "pleb" - the word judged to have caused the political damage - but admitted swearing during the altercation with PC Toby Rowland.
Mr Mitchell with his bike at the gates of Downing Street
Following the incident Wallis, a member of the Metropolitan Police Diplomatic Protection Group, sent an email to the deputy chief whip John Randall, who was his MP, saying he had been sightseeing in the capital when he saw the row.
Wallis sent the email from a private address but it was quickly established that he was a serving officer and that he was not present at the gates of Downing Street during the incident.
At the Old Bailey today, Wallis, 53, of West Drayton, pleaded guilty to misconduct and the court heard that he would offer his resignation from the police force. He will be sentenced on February 6.
Andrew Mitchell at a press conference in November
Mr Mitchell, MP for Sutton Coldfield, said: "I am pleased that justice has been done in a criminal court today.
"It is very sad and worrying for all of us that a serving police officer should have behaved in this way. There remain many questions unanswered, in particular why PC Wallis wrote this email and who else was involved in this process."
Prime Minister David Cameron said: "It is completely unacceptable for a serving police officer to falsify an account of any incident.
"Andrew Mitchell has consistently denied the version of events presented in the email and I welcome the fact that the officer concerned has now pleaded guilty."
The case and the subsequent police investigation into the incident have been acknowledged by the Metropolitan force to have significantly damaged the public trust in it.
Mr Mitchell's resignation letter to David Cameron
The guilty plea comes as the Met is facing a fierce backlash over the case of Mark Duggan, who was shot dead by officers on the streets of Tottenham and whose killing sparked the London riots in 2011.
An inquest jury this week concluded Mr Duggan was lawfully shot but there remain significant questions over the police handling of the case and claims regarding collusion over the evidence of officers.
Speaking after the guilty plea, Met Police Commissioner Sir Bernard Hogan-Howe said: "This investigation has been a ruthless search for the truth as at the heart of this are extremely damaging allegations that officers have lied and falsified statements against a Cabinet Minister.
"The evidence against PC Wallis was such that he has entered a guilty plea.
"To lie about witnessing something and provide a false account falls way below the standards that I and PC Wallis's colleagues expect of police officers.
"His actions have also negatively impacted upon public trust and confidence in the integrity of police officers.
"I would also like to apologise to Mr Mitchell that an MPS officer clearly lied about seeing him behaving in a certain manner. I will be writing to him offering to meet and apologise in person.
"I expect my officers to serve the public without fear or favour. Where officers break the law, they must expect to be held to account and answer for what they have done."
The investigation into the Plebgate incident has cost the public more than £300,000 and involved 1,100 statements being taken and 439 exhibits seized.
Mr Mitchell has always claimed he was "stitched up" and that he was a victim of police revenge for Government-led cuts.
In November, the Crown Prosecution Service announced that it had no evidence to suggest that PC Rowland was involved in any wrong-doing and there is nothing to suggest he knew about the Wallis email.
Last month the officer announced he was suing Mr Mitchell for libel over comments made in the fall-out of the Downing Street incident.
Mr Mitchell announced in March that he was suing The Sun for libel over the original story.
In total, 11 officers face disciplinary proceedings in relation to the Plebgate story and risk losing their jobs.
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