A Met police officer who lied about witnessing the Andrew Mitchell 'Plebgate' affair has been sentenced to 12 months in jail.

PC Keith Wallis, 53, admitted a charge of misconduct in public office after falsely claiming to have witnessed an argument between the former chief whip and officers at the gates of 10 Downing Street in September 2012.

Wallis, of West Drayton, sent an email to his MP and then Mitchell's deputy chief whip John Randall claiming he had witnessed the confrontation between Mitchell and the officer at the gates.

Mitchell resigned from his role as chief whip despite frequently denying accusations he called the officers "plebs" during the argument.

He admitted swearing at the officers but strenuously denied using the term "pleb".

Speaking after the sentencing, Mitchell warned that if the police could lie about an incident regarding a senior politician, then it "can happen to anyone".

He added: "This whole sorry affair has been immensely damaging to everyone involved."

Wallis has now been sentenced to 12 months in prison after he falsely claimed to have seen the row.

Upon sentencing, Judge Justice Sweeney said Wallis' actions had fallen "far below the standards expected of a police officer".

He added: "Indeed it was a betrayal of those standards, and was misconduct which, as well as having had an impact Mr Mitchell himself, has had a significant impact on public trust and confidence in the integrity of police officers."

Deborah Glass, commissioner for the Independent Police Complaints Commission, added that Wallis had brought "shame upon the police service".

The Met Police has confirmed that Wallis will now be subject to a misconduct hearing.

Commissioner Sir Bernard Hogan-Howe said: "PC Wallis's actions have clearly fallen way below the standards that me, my fellow police officers and the public demand.

"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.

"I apologised personally to Mr Mitchell that an MPS officer clearly lied about seeing him behaving in a certain manner. Today, I apologise to the public for PC Wallis's behaviour."