The policeman at the centre of the Plebgate row is demanding up to £200,000 in compensation from the MP for Sutton Coldfield Andrew Mitchell.
Toby Rowland has filed court papers repeating his claim that Mr Mitchell used the term "plebs" during their confrontation in Downing Street in 2012.
He also argues that the then chief whip, who was forced to resign in the wake of the controversy, changed his story after effectively admitting in a phone call that he had said the disputed words.
The documents have been lodged as part of a libel battle between the MP, the police officer, and The Sun newspaper.
Stating his case in detail for the first time since the incident, Mr Rowland insists Mr Mitchell erupted after being blocked from cycling out of the pedestrian gate to leave the street.
The politician has previously admitted to using "Anglo-Saxon" language, but said he did not swear at police, and denied using the term "plebs".
Sutton Coldfield MP Andrew Mitchell has received a formal apology from the Chief Constable of the West Midlands over the involvement of one of his officers in the plebgate affair.
Chris Sims visited Mr Mitchell at his constituency office today.
The apology is the latest from senior police staff. Mr Mitchell has always denied calling Downing Street police officers 'plebs'.
The Chief Constable of West Midlands Police, Chris Sims, is expected to apologise to Sutton Coldfield MP Andrew Mitchell today, over the role of one of of his officers in the 'Plebgate' affair.
Earlier this month, Mr Mitchell received an apology from Scotland Yard Chief, Sir Bernard Hogan-Howe, where they agreed on the importance of 'drawing a line' under the matter.
A former policeman at the centre of the "plebgate" row has said officers on duty at the gates of Downing Street have been "betrayed" by their Metropolitan Police bosses.
Ian Richardson said he believes his colleagues' claims that Andrew Mitchell called officers "plebs" and was "officious and rude", in an interview with The Times.
Despite not hearing the exchange, Mr Richardson said Pc Toby Rowland, the officer who claims he was sworn at by Mr Mitchell, immediately recounted what was allegedly said.
Mitchell, the Conservative MP for Sutton Coldfield, admits swearing at the officers but maintains that he did not use the other words attributed.
Mr Richardson accused the Metropolitan Police of failing the officers involved by concentrating on who leaked the story to the media rather than investigating what had happened and issuing a statement to clarify the incident.
The former officer, who retired with 30 years' service in October 2012, said Mr Mitchell should not have lost his job over a "quirky incident that should have blown over".
The ripples from Andrew Mitchell's short, bad tempered altercation at the Downing Street gate continue to spread.
ITV News has learned that the police watchdog has temporarily suspended its investigation into three police union representatives over their meeting with Mr Mitchell.
The officers from Mr Mitchell's local Police Federation branches gave an account of a meeting with him about the 'Plebgate' affair, which appeared to contradict a recording Andrew Mitchell made of the meeting.
The Independent Police Complaints Commission launched an investigation into the men after they appeared in front of the Home Affairs Select Committee. But the Federation then initiated legal proceedings saying the men had already been investigated and cleared.
The Federation took out an injunction against the IPCC investigation while a Judicial Review is heard. An IPCC source says it will not harm their investigation to wait for the outcome of the review and so they are not contesting the injunction.
An IPCC spokesman said: "We deeply regret the delay in concluding a matter of great public interest.
"However, as there would be no prejudice to our investigation if it is suspended pending the outcome of proceedings we do not wish to incur unnecessary costs from the public purse in fighting the interim application.
"As a result, we will not be in a position to complete our investigation pending the conclusion of this legal action."
The Federation has supported Pc Rowland with the provision of legal advicein respect of this matter. All subscribed members of the Police Federation areentitled to such support for legal representation as they see fit.
Andrew Mitchell said last week that he hoped Pc Toby Rowland would give evidence on oath as part of separate libel proceedings against the Sun newspaper.
Mr Mitchell told Channel 4 News: "What I do know is that I was stitched up; I was fitted up in Downing Street by armed police officers ...
"We believe that the CCTV shows that the account of Pc Toby Rowland is at very best inaccurate."
The police officer at the centre of the 'Plebgate' affair has filed a defamation case against former Tory Whip Andrew Mitchell, the Metropolitan Police Federation has confirmed.
Pc Toby Rowland, who has made the claim, was the officer on the Downing Street gate when Mr Mitchell was forced to push his bike through the pedestrian exit.
Mr Rowland's account of the altercation that followed differs from that of Mr Mitchell, but the Crown Prosecution Service decided there was not enough evidence to show which one was correct.
Andrew Mitchell will not be able to recover his legal costs of he wins his libel case against The Sun newspaper over the Plebgate affair, the Court of Appeal said today.
The Court of Appeal refused to overturn a ruling from High Court judge Master Victoria McCloud imposing the punishment after Mr Mitchell's lawyers failed to submit a budget for £506,425 of costs on time.
The ex-cabinet minister, who revealed his personal anguish over the affair yesterday, is suing The Sun over its report on September 21 last year about the incident at the gates of Downing Street which led to the so-called "Plebgate" affair.
It is unclear whether the MP, who was reported to be on a no-win no fee arrangement, will now need to meet the legal bill from his own pocket.
The officer at the centre of the "plebgate" row Toby Rowland has stuck by his version of events, and said he would be prepared to give evidence under oath.