An engineer accused of assaulting a lawyer outside a bar in Parliament has been cleared by a jury.

Ronald Freeman, 57, of Borehamwood, allegedly shoved Peter Brooksbank to the ground leaving him needing between 12 and 20 stitches to his head on December 5 last year, a court heard.

The alleged incident occurred outside the Sports and Social bar within the grounds of the House of Commons in London, where the two men had been drinking.

Mr Freeman had denied one count of assault occasioning actual bodily harm, saying his initial interaction with Mr Brooksbank had been to check if he was all right.

A jury at Southwark Crown Court took less than an hour on Friday to reach its decision of not guilty.

Mr Freeman, standing in the dock, did not react as the unanimous verdict was given.

Giving evidence during the trial, Mr Freeman claimed a "dishevelled" Mr Brooksbank had reacted aggressively when he had put his hand on his shoulder in the smoking area outside the bar.

"He started shouting at me, 'What do you think you're doing?'," he told the jury. "There was the f-word, f****** idiot, imbecile."

The court heard that despite another contractor trying to "calm" the situation, Mr Freeman said Mr Brooksbank had continued swearing at him in a "posh way, posh derogatory".

Mr Freeman, who had been at an engineers' reunion dinner in Parliament, had drunk around four glasses of red wine and a pint of Guinness before his first interaction with Mr Brooksbank, the court heard.

Mr Brooksbank, a lawyer who works as deputy counsel to the joint committee on statutory instruments, who was seen on CCTV entering the bar at 3.40pm, had drunk three pints of Guinness before the incident, the court heard.

He told the court that after the encounter in the smoking area, Mr Freeman yanked his parliamentary pass off his neck and took it to another part of the building.

Mr Brooksbank followed to retrieve his pass and left the room, before allegedly being assaulted in an alleyway, the court heard.

He claimed Mr Freeman pushed him from behind, causing him to hit his head on paving stones and be left swollen and "black all over".

Mr Brooksbank said he was treated by a paramedic and taken to Guy's and St Thomas' Hospital where he received between 12 and 20 stitches to his head, the court heard.

During the trial Labour MP Andy Slaughter also gave evidence about an incident around a decade ago when he said he was shoved and shouted at by Mr Brooksbank.

The court heard Mr Brooksbank on that occasion accepted he called the MP a "f****** idiot".

The lawyer wrote a letter of apology to the MP following an investigation by the Serjeant at Arms.

At the conclusion of the trial Judge Gareth Hawkesworth thanked the jury and order Mr Freeman be paid £126 to cover travel costs.