King Charles travelled to Sandringham after meeting his son, Prince Harry, who flew in from US.
The Duke of Sussex has arrived in the UK to visit his father following the King’s cancer diagnosis.
Prince Harry arrived in London on Tuesday after an overnight flight from Los Angeles.
The King, 75, informed both of his sons about his diagnosis before Buckingham Palace announced he would step back from public duties for treatment.
The Duchess of Sussex is expected to remain in the US, where the couple live with their two young children.
The speed with which Prince Harry has hurried from California to visit his father in the UK appears significant.
There had already been signs of the family getting closer, such as when the duke, 39, spoke with the King by phone for the monarch’s birthday last autumn.
But there were no signs of Prince Harry or Meghan heading over for Christmas or for any other family get-togethers. Until now they had stayed an ocean apart from the rest of the Royal Family.
Tensions in the Royal Family – as reported in Prince Harry’s memoir Spare – seemed not so much between him and the King, but rather with his brother the Prince of Wales and fuelled by the excesses of the tabloid press.
To that end, Prince Harry’s recent trips to the UK have been more about law courts than the royal courts.
But even before this latest health news, Prince Harry and Meghan – who live in the exclusive Californian community of Montecito – seemed to be planning more projects and travel.
They travelled to Jamaica for a film premiere and had said they would be in Canada later this month, in an event related to their Invictus Games. That trip is still expected to go ahead.
King Charles’s cancer diagnosis
Prince Harry’s brother, Prince William, is yet to comment publicly on the King’s diagnosis.
Prince William is expected to take on some of his father’s public engagements during the King’s absence, though the Palace has stressed the monarch will continue to carry out formal constitutional functions.
The prince was already due to return to his own public duties this week after stepping back following the Princess of Wales’s abdominal surgery last month.
On Tuesday morning, the King’s niece Princess Beatrice was seen arriving at Clarence House, the London residence where the King is staying following his first round of treatment.
Prime Minister Rishi Sunak earlier told BBC Radio 5 Live the King’s cancer had been “caught early” and said he was still in “regular contact” with the monarch.
He said their weekly audiences would continue to take place during the King’s treatment.
The Palace has disclosed few details about the King’s cancer diagnosis, other than to confirm it was discovered during a recent procedure to treat an enlarged prostate.
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