At what point do you admit that one of your longest standing friendships, which you’ve shared since way back when, has finally run its course?

You stood by your old mate after he lost his job and went off the rails - even when he refused to accept he’d been sacked and had to be escorted from the building by security kicking and screaming.

You gave him the benefit of the doubt when he was accused of paying off that porn star - I mean who hasn’t, right? And all that stuff about getting prostitutes to urinate on a hotel bed, well that was clearly fiction although, given all the stories he’s told over the years, you wouldn’t put it past him.

The final straw was when he was ordered by a court to pay more than £60 million to a woman who accused him of raping her and then defamed her by suggesting she’d made it up. No, a pal’s a pal, but the next time he suggests meeting for a pint, you’re definitely going to blank him.

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If only it was that simple. If only those were the only considerations for the UK in deciding its future ties with Donald Trump’s America, should the businessman be re-elected as President in the autumn.

Relationships between states are more complicated and consequential than personal ones, particularly when they involve the so-called "special relationship". At stake are not just diplomatic, economic, and cultural ties between the two countries, there is also our position as America’s closest ally and our place at the pivot of global defence and security arrangements.

While the US election is still 10 months away, and Trump has yet to officially win the Republican nomination, polling indicates he may well be re-elected on November 5.

This is despite New York Attorney General Letitia James launching a civil action accusing the businessman and his adult sons of fraudulently inflating his net worth to secure advantageous loan terms and insurance policies.

Manhattan District Attorney Alvin L Bragg, meanwhile, has filed criminal charges related hush-money, allegedly paid to porn star Stormy Daniels, aimed at covering up a potential sex scandal and facilitating Trump's 2016 presidential bid.

Special Counsel Jack Smith has brought further charges against Trump, claiming he mishandled classified documents and also that he attempted to overturn the 2020 election results.

In Georgia, the former president faces charges of orchestrating a "criminal enterprise" to overturn the state's election results.

The legal battles raise questions about the potential impact on Trump's political future and his ability to appear on state ballots, especially in light of his alleged role in inspiring the violence at the Capitol on January 6, 2021.

The Herald: Donald Trump at Trump Turnberry in 2015Donald Trump at Trump Turnberry in 2015 (Image: Getty)

If he becomes the first convict to be elected president – or the first president under indictment – it will pose a number of practical and ethical challenges for both the UK Prime Minister and the Scottish First Minister.

Normally, British governments can hold their noses when dealing with foreign dictators of whose actions they disapprove, such as the leaders of China and Saudi Arabia, because of the negative economic consequences of doing otherwise.

Such leaders are never convicted of anything, principally because they control the judiciaries of their countries.

Having criminal convictions would not prevent Trump from becoming President and the likelihood of it impacting on his efforts to secure the GOP nomination are low. He would likely appeal, potentially to the US Supreme Court, which currently holds a conservative supermajority. There is also the theoretical possibility of him pardoning himself, although this legal concept remains untested.

Even with a felon as a president, it seems inconceivable that Britain would have anything other than normal diplomatic relations with the US, but should it roll out the red carpet for Trump in those circumstances?

Recent dealings between the two countries suggests that the "special relationship" only cuts one way.

Despite the UK’s slavish backing for every major US-led military engagement since Vietnam, when Theresa May sought support from Trump following the Putin-sponsored Novichok nerve agent attack in Salisbury in 2018, he made clear to her he would wait to see what EU leaders did before agreeing to expel Russian diplomats from Washington.

The then-President constantly grumbled about America’s disproportionate spending on defence, compared with its allies, and he even discussed with aides the possibility of the US withdrawing from Nato.

Relations under Joe Biden’s presidency have, if anything, been even cooler, with no sign of a post-Brexit trade deal between the two countries being agreed anytime soon.

If the boot was on the other foot, it is less than certain a UK prime minister with criminal convictions would be allowed to enter the US. A report to Congress in July 2021 identified 55 government officials, including current and former ministers as being ineligible to enter the country due to ‘credible allegations of corruption’.

Last year Humza Yousaf said he would find it difficult to meet Trump, given his past comments about Muslims.

But could the Scottish Government overcome its reluctance to investigate questions of potential financial impropriety over Trump’s purchase of golf courses in Aberdeenshire and Ayrshire?

In 2006, the businessman bought land on the Menie Estate for £7m and, after spending £150m on planning and construction, the Balmedie course opened in 2012. Two years later, he purchased the Turnberry Golf Club, which has hosted four British Opens Championships, for £50m.

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Last year Allen Weisselberg, a key figure in the Trump Organisation and a former manager of the Balmedie course, was convicted for his role in a 15-year tax fraud scheme. The Turnberry course is currently embroiled in James’s civil action, over allegedly false financial statements made by the Trump Organisation.

Non-profit transparency campaign group Avaaz has urged the Lord Advocate to issue an unexplained wealth order against Trump, regarding the purchase of the two courses.

It suggests funds did not come from legitimate sources, but rather from business deals in Russia and the Cayman Islands, a renowned tax haven, which the Trump Organisation denies.

Last year tax returns for Donald J Trump Holdings for 2015-20, published by the Senate's ways and means committee, revealed a £45million black hole, including a £7.9m loss for Turnberry in 2020 – and a £38.3m deficit over six years – while losses at Balmedie totalled £7.3 million over four years.

If even some of the allegations against Trump are proved to be true, then it may be time for the UK to look again at the value of the special relationship. With friends like that, who needs enemies?