TV presenter Dr Christian Jessen has been ordered to pay damages of £125,000 to Arlene Foster for posting an “outrageous” defamatory tweet which made unfounded claims that the First Minister of Northern Ireland was having an extramarital affair.

Mrs Foster’s lawyer welcomed the judgment, stating that he believed it was a “watershed” moment for women in public life who have been attacked on social media.

Delivering judgment in the case at the High Court in Belfast, Mr Justice McAlinden accepted that the false tweet by the celebrity doctor had cut Mrs Foster “to the core”.

Mrs Foster sued Dr Jessen, best known for appearing in the Channel 4 show Embarrassing Bodies, after the tweet on December 23 2019, making the false allegation of an affair to his 300,000-plus followers.

The tweet remained online until Dr Jessen deleted it on January 7 2020.

Delivering judgment, Mr Justice McAlinden said: “To state that a woman married for 25-and-a-half years and a mother of three children, who is a committed Christian and who is recognised as such, and who has publicly made statements extolling the importance and sanctity of marriage, who also happens to be the leader of the Democratic Unionist Party and a holder of the office of First Minister of Northern Ireland, was an adulterer, a hypocrite and a homophobe is a most serious libel and is grossly defamatory.

“It is an outrageous libel concerning an individual of considerable standing, attacking her integrity at the most fundamental level, and it involves the trashing in a very public fashion of the relationship that Mrs Foster holds dearest in her life.

“It affected core aspects of her life, namely her relationship with her husband, her deep Christian faith, it called into question her fitness and suitability to occupy the office of First Minister at a time when delicate negotiations were continuing on the re-establishment of the Northern Ireland Executive.

“In short, I consider that it was an outrageously bad libel.”

The judge also addressed the fact that Dr Jessen failed to respond to warnings from Mrs Foster’s lawyer about the tweet.

He continued: “The offending tweet remained on the defendant’s Twitter account for two weeks, a Twitter account with 311,000 followers.

“This outrageously bad libel cut her (Mrs Foster) to the core, causing her considerable upset, distress, humiliation, embarrassment and hurt.

“Her marriage, her family life and her faith are the most important things in her life. These things provide important pillars of support and it was these things that were publicly trashed.”

The judge referred to evidence given by Mrs Foster suggesting the timing of the tweet may have been deliberately chosen to undermine negotiations concerning the restoration of the Northern Ireland Executive.

He said: “I do not ascribe to the defendant having the knowledge of, or interest in Northern Ireland politics which would be a prerequisite to giving any detailed consideration to the possibility that the timing of this tweet was intended to influence the outcome of the negotiations.

“However, in respect of the anonymous tweets which preceded the defendant’s much more prominent statement, such a motivation cannot be dismissed out of hand.”

Mr Justice McAlinden ordered Dr Jessen to pay damages of £125,000 and Mrs Foster’s legal costs.

Giving evidence last month, Mrs Foster told the court she was left humiliated by the unfounded rumour of an affair with a close protection officer which “trashed” her 25-year marriage.

Speaking outside the High Court, Mrs Foster’s solicitor Paul Tweed said: “My client is very satisfied with the substantial sum in damages awarded by the court today. Indeed I believe this is a record award for a tweet.

“The award also takes into account a number of aggravating factors in this case, including Dr Jessen’s failure to retract and apologise.

“Dr Jessen has been offered every opportunity to do the right thing in this regard from the outset, but he has pointedly failed to do so.

“My client is grateful to the court for this total vindication which hopefully will also act as an encouragement and a watershed for all women in public life who have been subjected to similar attacks on social media.”

He added: “I would just say one thing personally. On Christmas Day 2019, in response to the warning I had given to Dr Jessen, he tweeted ‘Laugh Out Loud’.

“I don’t think he will be laughing too much today.”