The allegations made by the newspaper in its article were vicious, vitriolic and attacked his personal character in the very worst way

It might strike the court as surprising that a person who enjoys a level of success and influence as this claimant would choose to spend somewhere in the region of £1 million litigating to trial the question of whether these short passages represent an opinion an honest person could have held

He added that an “honest opinion is supposed to give latitude but it is not a licence for a journalist to mislead the reader.”

Mr Rushbrooke also pointed out the word “screwed” could be seen as meaning “underhand and discreditable”.

However, the barrister described Sir James as a “British success story”, with the court told the inventor has provided opportunities for young people in the UK, particularly as regards their education and training, and is widely involved in many philanthropic activities.

In a statement, a Dyson spokesman said Sir James had brought the legal claim “as a last resort”.

The spokesperson continued: “The Mirror Group Newspapers has admitted to the Court that Sir James is recognised as one of the UK’s greatest ever inventors and business leaders and that he is one of the UK’s leading philanthropists, particularly in the educational fields, yet the allegations made by the newspaper in its article were vicious, vitriolic and attacked his personal character in the very worst way.”

However, Adrienne Page KC, for MGN, said in written submissions that Sir James’ approach to the legal claim “has been markedly unreasonable, wholly disproportionate and abusive”.

She continued in written submissions: “It might strike the court as surprising that a person who enjoys a level of success and influence as this claimant would choose to spend somewhere in the region of £1 million litigating to trial the question of whether these short passages represent an opinion an honest person could have held.”

The barrister said that an honest person “could, self-evidently have held the opinion”.

Ms Page continued: “Opinions do not need to be justifiable as the claimant puts it, they need to be capable of being held by a person who is honest.”

“It was a genuinely and indeed widely held view that the decisions relied on represented a betrayal of this country made particularly acute by the claimant’s prior and influential support for a political position which, in the eyes of many, has caused this country severe economic harm.” 

The trial before Mr Justice Jay is set to conclude on Friday with a decision expected at a later date.