An engineer accused of assaulting a lawyer in a Parliament bar was sworn at by the alleged victim "in a sort of posh way", a court heard.
Ronald Freeman is accused of leaving Peter Brooksbank's face "black all over" after pushing him to the ground in the House of Commons on 5 December.
Mr Freeman, 57, of Borehamwood, Hertfordshire, told Southwark Crown Court Mr Brooksbank reacted aggressively after checking he was OK.
He denies actual bodily harm.
Mr Freeman told the court he had been attending a reunion dinner in the Strangers venue at Parliament and had drunk about four glasses of red wine and a pint of Guinness before the pair's first interaction.
The engineer, who had worked as a contractor in Parliament for 11 years, said he had approached a "dishevelled" Mr Brooksbank as the lawyer sat on a step, putting his hand on his shoulder to check if he was alright.
He said Mr Brooksbank started shouting at him, saying: "What do you think you're doing?"
Despite another contractor stepping in to "calm" the situation, Mr Brooksbank was "still swearing, in a sort of posh way, posh derogatory", Mr Freeman told he jury.
He added: "There was the f-word... idiot, imbecile."
The court has previously heard Mr Brooksbank, a lawyer who works with a group of MPs and peers that scrutinises secondary domestic legislation, was assaulted after following Mr Freeman who had yanked his Parliamentary pass off.
He was then assaulted in an alleyway and needed 12 to 20 stitches, the court heard.
Labour MP Andy Slaughter also gave evidence about an incident from a decade ago involving Mr Brooksbank, having heard of the alleged assault by Mr Freeman in the newspaper reports about the trial.
Mr Slaughter, who represents Hammersmith, said he had been shoved, shouted and sworn at by Mr Brooksbank, who he recognised from a select committee, at Westminster Tube station.
He said: "I was shocked that it was someone who was an officer of the house, somebody who had an important position there and I just thought it was totally inappropriate behaviour."
Mr Slaughter said he later received a letter of apology from Mr Brooksbank and had never met Mr Freeman.
The trial continues.