The Metropolitan police officer who pretended to have witnessed the Downing Street altercation which led to Andrew Mitchell's resignation has been jailed for 12 months.
PC Keith Wallis, 53, of West Drayton, would have received 18 months behind bars had he pleaded guilty, he was told by the judge at the Old Bailey.
But Wallis, who admitted misconduct in a public office and was heard to apologise repeatedly in a police interview, was instead sentenced to 12 months behind bars.
"You have lost your good character and are bound to be dismissed from the police," Mr Justice Sweeney told Wallis.
"Police officers must be deterred from misconduct and the public must see they will be punished if they are not."
The diplomatic protection officer was off duty at the time of the incident and claimed he was a member of the public sightseeing outside Downing Street with his nephew when the incident occurred.
Mitchell strenuously denied using the word 'pleb', against the evidence of Wallis' email. But he admitted swearing and was subsequently forced to resign over the incident. He has not returned to the government since.
"I was eventually 100 per cent convinced I was there. I thought in a roundabout way I was backing up my colleagues but I wasn't ... it all exploded," Wallis told colleagues in a police interview heard by the court.
"For sometime afterwards I convinced myself I was doing the right thing but I now know I wasn't. All I can say is that I'm really sorry, really sorry."
Met police commissioner Bernard Hogan-Howe apologised to Mitchell in person yesterday.
The Independent Police Complaints Commission's Deborah Glass said there was not evidence of an organised conspiracy to bring down a Cabinet minister, but she said there was "clearly collusion between certain officers" which "ultimately had the same effect".
Wallis is the only police officer to have been punished in relation to the scandal.
Glass added: "The actions of PC Wallis, and the other officers responsible for turning a largely inaudible altercation lasting less than a minute into a national scandal, have not only caused injustice to Mr Mitchell, they have brought shame upon the police service."
Wallis, who is now behind bars, supported the jail sentence.
His barrister, Patrick Gibbs QC, had told the court: "Mr Wallis would like you to send him to prison because he thinks that everyone would be better off without him."