When Donald Trump’s helicopter touches down in the gardens of Buckingham Palace on Monday morning, he will become only the third US President to enjoy the full trappings of a state visit to the UK.
He’s the Queen’s 13th US President and she’s met all of them at some point in the last 67 years, apart from Lyndon Johnson.
Mr Trump has been here before, of course.
But last year, when he awkwardly walked across the Queen’s path during the Guard of Honour at Windsor Castle, Mr Trump was in the UK on a working visit.
This time, it’s different.
This time the real red carpet treatment is being laid on.
No country does a state visit quite like the UK.
And no one knows how to do them quite like the Queen.
She will not be in the least bit fazed by Mr Trump and his family, no matter how controversial and divisive a politician he has proved to be.
The Queen has dealt with many a tricky state visit.
They began four years after she acceded the throne in 1956.
Soviet leader Nikita Khrushchev arrived in the country at the height of the Cold War.
UK-Soviet relations became immediately tense after a British Navy diver died in Portsmouth Harbour trying to spy on the military cruiser which had brought Mr Khrushchev to Britain.
Then in 1958, the Queen hosted the German President, at a time when the memories of the Second World War were still fresh in so many minds – peace had only arrived 13 years earlier.
Similarly, in 1971 a state visit by Emperor Hirohito of Japan triggered many protests from former prisoners of war who’d suffered at the hands of the Japanese military during the World War II.
But no visit was as difficult for the Queen as the one by Nicolae Ceaușescu.
The controversial and brutal Romanian leader was invited here to help cement a deal for military jets.
But even the then Labour government was regretting the invitation by the time the Ceaușescus arrived in London in 1978.
In fact, the Queen had received so many briefings about his unpleasant manner and the dreadful behaviour of his entourage that she had all the valuables removed from the guest rooms in Buckingham Palace (they were known for stealing them) – and she famously hid behind a bush in the Palace gardens when she spotted the dictator and his wife walking her way - to avoid having to spend any more time with them than was absolutely necessary.
So this week’s State Visit by Donald Trump and his wife Melania (and several members of the Trump family) will be a walk in the park for our 93-year-old Monarch.
She’s not even having to put them up because the redevelopment work at Buckingham Palace has taken out the entire East Wing (the bit most of us see with the famous balcony).
Instead, this week the Trumps will stay at the official residence of the US Ambassador, Winfield House, in Regent’s Park (it’s a sizeable property so there will be plenty of room).
But what Britain will be doing – Guards of Honour, State Banquets, private lunches, Royal Family teas, Westminster Abbey visits – will give the Trumps exactly what they’ve come for: pictures to beam back to America with the most famous royal family in the world.
And while discussions with Prince Charles might prove a little tricky on some subjects (climate change being the most obvious one) there won’t be any diplomatic difficulties with Mr Trump’s fellow American: the Duchess of Sussex.
Meghan is on maternity leave so has the perfect excuse for missing the entire visit.
The Duchess previously called Donald Trump (when he was a Republican nominee for President) "divisive" and "misogynistic".
And while the Trump’s arrival will trigger protests in London, and there will be much analysis of any meetings with Boris Johnson or Nigel Farage, the US President won’t care about any of it.
He’ll be focused on that royal red carpet and on the commemorations on both sides of the English Channel later in the week to acknowledge the sacrifice and service of the men and women who took part in the D-Day landings 75 years ago.
And The Queen will simply notch up yet another state visit, by yet another world leader in her long, long reign.