The King returned to London on Tuesday as he prepares to undergo further treatment following his cancer diagnosis.
Charles and Queen Camilla flew by helicopter to Buckingham Palace from their private Sandringham home on Tuesday morning. They were then driven the short distance to nearby Clarence House.
It was announced last week that the head of state has a “form of cancer” and at the weekend he issued a statement praising “all those organisations which support cancer patients”.
Charles has postponed all public-facing duties, but is continuing with behind-the-scenes work on his red boxes of state papers.
The Queen has been carrying out her royal diary of engagements and last week said her husband was doing “extremely well under the circumstances”.
She said the King, who underwent his first bout of cancer treatment last week, had been “very touched” by all the messages of support he has received from the public.