KING Charles hosted EU boss Ursula von der Leyen for tea at Windsor Castle today.
The EU Commission leader was in town to seal a new post-Brexit Northern Ireland deal with the PM, Rishi Sunak.
The King was snapped meeting with Ms Von Der Leyen in Windsor Castle this afternoon for an audience with His Majesty.
But the move sparked a row with Tory and DUP politicians - saying it was unfair to drag the King into politics.
And the PM came under fire after Buckingham Palace said the monarch was acting on “the Government’s advice”.
Ex-Cabinet Minister Jacob Rees-Mogg said the talks would have “antagonised the people” Mr Sunal needs to win over.
He said: “It is also constitutionally unwise to involve the King in a matter of immediate political controversy."
Northern Ireland’s former First Minister Arlene Foster piled in: “I cannot quite believe that No 10 would ask HM the King to become involved in the finalising of a deal as controversial as this one. It's crass and will go down very badly in NI.
"We must remember this is not the King's decision but the Government who it appears are tone deaf."
DUP chief whip Sammy Wilson warned the meeting risked “dragging the King into a hugely controversial issue”.
As head of state Charles must stay politically neutral and Downing Street defended advising him to meet Ms von der Leyen.
Mr Sunak’s spokesman said: “He firmly believes it's for the King to make those decisions.
“It's not uncommon for his majesty to accept invitations to meet certain leaders.”
Pressed on why the deal was signed in Windsor, he insisted it was often that high-level talks would be held in “significant locations”.
No10 insisted last night that any meeting with the King would be totally separate to the Northern Ireland agreement.
A Palace spokesman said: "The King is pleased to meet any world leader if they are visiting Britain and it is the Government’s advice that he should do so."
Mr Sunak and EU chief Ursula von der Leyen met at lunchtime to iron out the final details of an agreement on the Northern Ireland Protocol.
The pair conducted a joint press conference in Windsor - before the PM dashed back to Parliament to speak to MPs and sell the deal to them.
Q&A: SO WHY DID IT ALL DRAG ON?
Q) What is the Northern Ireland protocol?
A) It is a deal with the EU to avoid a hard border on the Irish mainland.
The EU insists goods which could enter its single market in the Republic of Ireland comply with its rules.
The protocol allowed some checks to take place on goods travelling from Great Britain to Northern Ireland.
Q) What's the problem?
A) The protocol created a border in the Irish Sea, splitting off NI from the rest of the UK.
Sometimes the checks are so onerous businesses on the mainland refuse to sell goods in NI, leading to shortages.
Q) How is PM Rishi Sunak proposing to fix this?
A) The EU will agree to a new system of red and green lanes. Goods from GB destined for NI only would be subject to minimal checks.
There will also be a Stormont lock to give elected politicians in NI a say over which EU rules they follow.
Q) Will this end the row?
A) Unlikely. Anything requiring NI to still follow EU rules on product standards will be unacceptable to many.
The EU and Britain have been striving to secure a new arrangement before the 25th anniversary of the Belfast Good Friday Agreement in April to smooth trade problems over the border and get the government in Stormont back up and running.
Following hours of negotiations, Brussels agreed to a new system of red and green lanes for goods crossing from Britain into the province.
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Products destined for NI only will be subject to minimal checks in the green lane, while those heading to the Republic will go through customs checks in the red lane.
There will also be a "Stormont lock" to give elected politicians in NI a say over which EU trade rules they follow.
Mr Sunak's new deal won't get a tick of approval from everyone.
Some members of the Brexiteer European Research Group have marked any involvement of the European Court of Justice in the province as a red line.
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Unionist MPs have said the same, however they'll wait to read the fine print before confirming disapproval.
All eyes will also be on ex-PM Boris Johnson, who over the past week spoke out against Mr Sunak's efforts to end the dispute.