PC Wallis was not present during the "plebgate" incident in September 2012
A Metropolitan Police officer who lied about witnessing the "plebgate" row has been sentenced to 12 months in prison.
PC Keith Wallis, 53, admitted a charge of misconduct in public office last month at the Old Bailey.
Wallis, of West Drayton, sent a senior Tory official an email wrongly claiming he had seen a row involving MP Andrew Mitchell in Downing Street.
The incident involved another officer who refused to allow the then chief whip to cycle through the main gate.
The Sutton Coldfield MP, who was forced to quit as the government's chief whip as a result of the ensuing fall-out, admitted swearing during the original incident but has denied the allegation by the officer present, PC Toby Rowland, that he had used the word "pleb".
After media reports of the incident in Downing Street, in September 2012, Wallis sent an email to John Randall, then Mitchell's deputy in the whips' office, claiming to be a member of the public who had witnessed the argument and heard Mr Mitchell use the word "pleb".
Andrew Mitchell was prevented from cycling through Downing Street's gates
He said he had been sightseeing near Downing Street with his nephew, when he was, in fact, off duty at the time and thought to have been nowhere near Downing Street.
Last month, the Old Bailey heard how Wallis, who is a member of the Metropolitan Police diplomatic protection group, admitted his offence in a police interview and offered to resign.
Mr Mitchell welcomed the guilty plea and there were calls for his return to government.
At the Old Bailey on Thursday, Wallis's lawyer, Patrick Gibbs QC, appealed for his client not to be sent to prison.
He said Wallis, who had served for 30 years in the police, had suffered from both mental and physical illness and had been deeply affected by the death of his father, also a police officer.
He added that Wallis had been drunk when he sent the email and that events had got "completely out of hand" afterwards.
He had come to convince himself that he had actually witnessed the false incident he had reported, Mr Gibbs said.
He told the court: "While it is impossible to pinpoint the moment Mr Wallis came to believe that video in his head, he did genuinely come to believe it."
Metropolitan Police Commissioner Sir Bernard Hogan-Howe apologised in person to Mr Mitchell on Wednesday, saying that Wallis's behaviour had fallen "way below the standards expected" of his officers.
Following the 50-minute meeting in Mr Mitchell's Commons office, where they agreed on the importance of "drawing a line" under the matter, Mr Mitchell said: "I am grateful to the Metropolitan Police Commissioner for his apology."