It’s had more "will he, won’t he" moments than a boardroom firing scene in Donald Trump’s previous role in The Apprentice.  But now, well over a year after he was first invited, US President Donald Trump is heading to the UK.

Theresa May was the first foreign leader to visit the new President in Washington in January 2017.  It’s fair to say Mrs May probably hadn't expected to walk hand in hand with Donald Trump in the grounds of the White House.

While the image may have received some ridicule back at home, Downing Street was quick to hail the visit as an acknowledgement of the special relationship between the UK and US.

In a time of Brexit, it’s a special relationship which is all the more important. Mrs May announced while there that she had extended an invitation to Mr Trump to visit the UK.

Not just a standard visit - never a low key affair for a US President anyway - but a state visit.  This would afford all the pomp and circumstance that any one person could want.

Mr Trump's mother, who emigrated from Stornoway in Scotland to the US as a young woman, had always been great admirer of Queen Elizabeth. 

A state visit meant Mr Trump meeting the Queen, and perhaps even a carriage ride through Windsor or London by her side.

 The decision to invite Donald Trump raised many questions for Theresa May back home, as she faced criticism for jumping in too fast and offering too much to a President who had not been long in the job, and polarised opinion. 

As the months went by, concrete plans for a state visit failed to materialise. If the proposed visit was unpopular to some in January 2017, the intervening months didn't help.

In that time Mr Trump refused to open the new US Embassy in the UK on the basis that it was in an "off location", blaming the Obama administration for selling "the best located and finest embassy in London for "peanuts," only to build a new one in an off location for 1.2 billion dollars".

"Bad deal" he tweeted adding: "Wanted me to cut ribbon-NO!".

The US President also retweeted three anti-Muslim videos from a far right group, causing outrage in the UK and prompting Theresa May to say publicly that he had done the wrong thing.

The Speaker of the House of Commons John Bercow said he would oppose Mr Trump addressing Parliament if he came to the UK. 

There has been continued speculation that Mr Trump is concerned about large scale protests against any visit by him.

What started as a relatively straightforward invitation in 2017 soon became a major diplomatic headache.  But now, headache or no, Donald Trump is on the way.

He will visit the UK on Friday 13 July, in a sign that neither he nor Downing Street are particularly superstitious.

His trip to Britain fits in with his return from the NATO summit in Brussels on 11-12 July.

It has been billed as a working visit, which will of course include talks with Mrs May.

Speculation is already rife that Mr Trump will meet Queen Elizabeth, although there will be no official state banquet or carriage ride down the Mall. 

While details are still being ironed out, it was clear Mrs May could not allow the visit to slip much further.

It had become a constant question from the media when Mrs May met President Trump at events such as the Davos World Economic Forum. 

A highly successful visit to France for Bastille Day last year by Mr Trump made it look as if French President Emmanuel Macron had stolen a march on the UK.

A return trip to Washington in recent days by President Macron only underpinned that notion further. 

For a UK which is keen to insist that it will remain a global power player after Brexit, this visit matters.

You can bet some pomp and circumstance will figure, working visit or not.