The Prime Minister has pulled out his 'Royal Trump card' - a smart political move in a game where President Trump has the upper hand.
The President of the United States has everything he wants: money, power, fame, and influence.
So what can Britain offer to strengthen the UK-US special relationship, progress with a tariff-free trade deal, and ensure Europe is protected from Russian aggression?
The answer is something money cannot buy: access to the Royal Family.
Starmer offers Trump something money cannot buy - access to the Royal Family
PA / Getty
Trump has a deep affection for the King and said it was a "great honour" to receive a personally signed invite from him during a meeting between Sir Keir Starmer and the President in the Oval Office on Thursday.
President Trump accepted the invitation, and it is understood there are also plans for an informal visit to Balmoral this summer; the only other sitting US president to receive an invite to the monarch's private Scottish retreat was President Eisenhower in 1959.
The State Visit itself is also "unprecedented", according to the Prime Minister, because never before has a US president received an invitation for a State Visit during their second term in office.
This could indicate the importance the Labour Government places on keeping President Trump onside, who is a Republican and would not naturally agree with centre-left policies.
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PAA lavish banquet at Windsor Castle and British military pomp and pageantry in his honour is something the President will embrace.
This is the power of the King's soft diplomacy, an asset the UK Government can deploy to elevate Britain on the world stage.
Already, this soft power appears to be paying off; President Trump and Sir Keir Starmer have agreed to begin work on a new US-UK trade deal at a time when the European Union is faced with the prospect of economically damaging tariffs.
On the US-UK deal, President Trump told reporters: “We could very well end up with a real trade deal where the tariffs wouldn’t be necessary.”
Trump has claimed he was the 'favourite' President of the late Queen's
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Donald Trump is a big admirer of King Charles
GettyPresident Trump has also appeared to back the Prime Minister's plan to give up sovereignty of the Chagos islands and lease back the UK-US Diego Garcia military base, saying the deal would "work out well."
The King's soft power, buttering up a royal-loving President Trump, can only go so far.
His Majesty remains above politics, and it is up to the UK Government, led by the Prime Minister, to thrash out the political details of any deals with their US counterparts.
