The King is set to move forward with plans to evict Prince Andrew from his Windsor mansion by the end of the year.
The Duke of York is expected to pay for the upkeep of the 30-room Royal Lodge – his home since 2003 – out of his own pocket.
But he is said to have provided little response to Charles’s questions over how he intends to cover the costs needed annually now that he is no longer a working royal.
The issue has not been forced while the beleaguered duke mourned his late mother and supported ex-wife Sarah, Duchess of York, who also resides there, through her breast cancer battle.
But the King, who has reportedly been covering the £3million annual cost of his brother’s security, does not have limitless pockets – and royal patience is understood to be wearing thin.
This means that Andrew, 63, faces stumping up the money himself, which royal insiders believe he simply does not have.
His Majesty is determined to press ahead and ask his younger brother to vacate Royal Lodge for a smaller, more affordable and better protected property on the royal estate.
Following the latest revelations over Andrew’s links with Epstein, multiple sources indicated to the Mail yesterday that the King was poised to take decisive action with regards to his brother.
One insider told the Mail: ‘The fact that his name appears on the [Epstein] list will be no surprise to anyone, least of all His Majesty.
‘But it will underline the need for him to maintain his [Andrew’s] ‘retired royal’ status.
‘No matter how much he wants to come back, this association is just never going to go away. And that means he [Andrew] has to.’
First and foremost that means no return to royal duties, despite recent speculation of a thaw in the prince’s exiled status.
Another source with understanding of the palace’s position on the matter says Charles has ‘long been firm on his thinking’ over this, even before he became King.
They added: ‘The duke was always very good at getting round their mother, the late Queen. Pressuring her quietly to support him. He was her achilles’ heel and she absolutely put her head in the sand over anything to do with him.
‘The King loves his brother and hates confrontation but has had to make a ‘business’ decision.’
There are no plans to strip Andrew of his HRH title, his dukedom – given to him as a wedding present by his mother – nor other honours such as the Order of the Garter.
However, he has been barred from using HRH publicly and for the past two years has been prohibited from joining senior royals for the Garter Day procession every June.
He is free to undertake private charity work, should any wish to work with him.
The biggest remaining question mark, therefore, hovers over the Lodge, the last vestige of his once-favoured royal status.
The King is unable to evict his brother, whose lease on the late Queen Mother’s home reportedly has 80 years left to run.
But Charles is able to demand that it is maintained to a high standard – and it is understood there is a significant backlog of essential repairs to be done.
Andrew has so far failed to adequately respond to requests to prove how he will able to afford these, as well as the ongoing upkeep of the vast house and gardens.
While the King hasn’t pushed the matter in recent months due to extenuating circumstances, it is understood that he will be doubling down for a resolution again this year. Events of recent days have only emphasised how important it is that this is sorted sooner rather than later.