Usually, correspondence written by the King is not made public, but Donald Trump held up the letter in the Oval Office.
Here is what we are able to make out from photos.
In the opening paragraph, the King references the “breadth of challenges across the world”, and says the UK and the US have “a vital role to play”.
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He goes on to say that he remembers “with great fondness” Trump’s visits to the UK during his “previous presidency”.
The King appears to suggest a visit Balmoral or Dumfries House in Scotland at some stage – estates owned or run by the monarch.
He writes: “There is much on both Estates which I think you might find interesting and enjoy – particularly as my Foundation at Dumfries House provides hospitality skills-training for young people who often end up as staff in your own establishments!
“Quite apart from this presenting an opportunity to discuss a wide range of issues of mutual interest, it would also offer a valuable chance to plan a historic second State Visit to the United Kingdom.
“As you will know, this is unprecedented by a US president. That is why I would find it helpful for us to be able to discuss, together, a range of options for location and programme content.
“In so doing, working together, I know we will further enhance the special relationship between our two countries, of which we are both so proud.”
Sky News has contacted Buckingham Palace to ask when the second state visit might take place, and they simply said: “When diaries allow.”
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