Police officer Susan Johnson has been sacked from the Met Police for gross misconduct because of her role in the Plebgate affair.
The officer, who serves on the diplomatic protection squad, was dismissed following a misconduct hearing which found she had "breached standards of professional behaviour".
The investigation into the altercation between the former Conservative Chief Whip Andrew Mitchell and a police officer at the gates of Downing Street found Pc Johnson had been involved in the leaking of information about the incident to The Sun newspaper.
Pc Johnson, who was not on duty at the time of the argument over cycling along Downing Street, was found to have been exchanging text messages and a phone call with someone who had then contacted the newspaper.
Andrew Mitchell at the gates of Downing StreetMr Mitchell resigned after details of his altercation with Pc Toby Rowland on September 19, 2012 emerged in which he was accused of using the phrase "f***ing pleb", a claim he has always denied.
The Conservative MP has always claimed the Police Federation used the incident to take revenge for police cuts and had orchestrated a "stitch-up".
Deborah Glass, of the Independent Police Complaints Commission, said earlier this year: "The patchwork of evidence from emails, text messages and telephone calls does not suggest an organised conspiracy to bring down a cabinet minister.
"But there was clearly collusion between certain officers to, as they saw it, blow the whistle on bad behaviour toward one of their own, which ultimately had the same effect."
Pc Keith Wallis was jailed for lying about the Plebgate affairPc Keith Wallis, another diplomatic protection officer, was jailed in February for lying about witnessing the heated exchange.
Pc Gillian Weatherley, who was on duty on the day of the incident, was sacked last month for leaking information to the press. She sent a picture of an email sent by Pc Rowland to his bosses to The Sun.
Following the jailing of Pc Wallis, Met Police chief Sir Bernard Hogan-Howe apologised to Mr Mitchell and to the public for the officer's behaviour.