A police officer who accompanied former Government chief whip Andrew Mitchell on two foreign trips has told the High Court that the MP was "unpleasant until he got what he wanted".
Inspector Duncan Johnston, who travelled with the then Secretary of State for International Development to Tunisia in March 2011 and Somalia and Kenya that summer, said: "Mr Mitchell seemed to have no regard for security and I felt as though my professional opinion was worthless.
"The way Mr Mitchell behaved led me to believe that Mr Mitchell thought that if he put enough pressure on us, we would do what we were told.
"He was prone to temper tantrums and, on the second trip, when he was yelling at anyone involved in arranging the visit, I felt he was verging on out of control.
"He was unpleasant until he got what he wanted. He would erupt but then minutes later he would be charming."
Mr Johnston, a police officer for 29 years who has worked in specialist protection for 15 of them, was giving evidence for News Group Newspapers (NGN) and Pc Toby Rowland.
Mr Mitchell, 58, is suing NGN for libel over a story about his encounter with Pc Rowland in Downing Street on September 19 2012.
He says the report in The Sun, which NGN says is substantially true, meant he was guilty of launching a grossly offensive and arrogant attack at police officers on duty, branding them "f****** plebs".
Asked if he had used the words attributed to him by Pc Rowland - "Best you learn your f****** place - you don't run this f****** government - you're f****** plebs" - he has told Mr Justice Mitting: "I did not say those words.
"I would never call a policeman a pleb, let alone a f****** pleb."
He has accepted that he did say, under his breath but audibly, "I thought you lot were supposed to f****** help us", but not at the officer.
Pc Rowland, who is in turn suing Mr Mitchell over statements he made from December 2012 which he claims accused him of fabricating his allegations, has told the court he gave Mr Mitchell a warning because members of the public were visibly shocked by the MP swearing at him.
Inspector Johnston said that, when he met Mr Mitchell at Djerba Airport, the 58-year-old MP for Sutton Coldfield ignored his outstretched hand and said "You must be the hired muscle" before diving into a group of refugees who "could have been anybody".
Inspector Johnston said he later told Mr Mitchell that it was not possible to visit Libya as it was not in his mandate and would breach international law.
The MP replied "That's a bit above your pay grade Mr Plod", said the officer.
He told the court today: "I don't think that the Mr Plod comment particularly upset me - I've been called a lot worse in my service. I don't think it was said to be unpleasant. It was either just misplaced humour or a put-down."
He added that, on the Somalia trip, Mr Mitchell launched in to a "foul mouthed tirade" as soon as he was met at the airport.
"He completely lost control of himself; so much so that I can't remember exactly what was said but he basically raised issues and questioned our actions and motives about the explanations given to the changes.
"He used a tirade of language that came quick and fast and was just swearing for the sake of swearing.
The officer said he had no personal grievance against Mr Mitchell, who wrote him a letter of thanks after the trip.
He said: "I can honestly say that I have never actually met anyone who is quite like Andrew Mitchell."
Lee Bryer, who used to be a security officer at Black Rod's Garden at Westminster, said that he had to yell out when Mr Mitchell cycled very fast through the closing exit barrier in November 2005, at a time of heightened security after the London bombings.
When he asked the MP to identify himself and explain why he had not stopped, Mr Mitchell replied: "I am a member of parliament and I am too important to stop for you", said Mr Bryer.
When Mr Bryer said he did not care who he was, Mr Mitchell allegedly told him: "Stop being so aggressive you little s***."
Mr Mitchell's counsel, James Price QC, said that he had no recollection of the exchange, which he branded a "caricature".
Written evidence was provided to the court by Conservative MPs Michael Fabricant and John Randall.
Mr Fabricant, the former government pairing whip, said that, in October 2012, he asked Mr Mitchell what he had said to the officers in Downing Street and it was clear he was unable to recall the exact words he had used - although he was adamant he had not used the term "plebs".
Mr Fabricant said that "Plebgate" had drowned out more constructive political stories.
"The incident was, in my view, not just embarrassing for Mr Mitchell, but it was deeply damaging and embarrassing for the entire Conservative party.
"As the weeks wore on following the incident, and the media did not appear as if it were going to let this story go, I formed the view that Mr Mitchell really should resign in order to put an end to it."
Mr Randall, who was deputy chief whip at the time, said that, in his view, whips should never be the focus of the media and the story was a "real disaster" for the Tory party.
When he spoke to Mr Mitchell, after it appeared, Mr Mitchell said he could not recall what he had said to Pc Rowland.
Mr Randall said: "In December 2012, I read a lengthy article published in The Sunday Times that was written by Mr Mitchell describing verbatim the exchange he had with the officer on the night of September 19 2012.
"I recall that I found the article, and in particular Mr Mitchell's account, rather extraordinary given Mr Mitchell's comments to me just five days after the incident that he could not recall what he had said."
The hearing was adjourned until Wednesday when counsel will make their closing submissions before the judge rules, on Thursday, on the meaning of the words complained of and whether they were substantially true.