King Charles has been pictured for the first time since his cancer diagnosis was announced on Monday evening.
Both he and Queen Camilla travelled to the royal estate in Sandringham by helicopter.
Earlier, Prince Harry arrived in London to visit his father – he flew in from his home in California.
Buckingham Palace announced the King’s cancer was found during his recent treatment for a benign enlarged prostate.
The monarch has postponed public duties, but will continue state duties and will still meet the prime minister weekly.
Timeline of King’s recent health treatment
17 January: Buckingham Palace announces that King Charles will attend hospital for treatment for an enlarged prostate the following week.
26 January: The King receives his treatment after being admitted to the London Clinic in the morning. Queen Camilla says her husband’s “doing well”.
29 January: The King leaves hospital after three nights. The Palace says he’ll have to postpone his public engagements “to allow for a period of private recuperation”.
31 January: Queen Camilla says her husband is “doing his best” after hospital treatment.
4 February: The King and Queen attend church in Sandringham, with Charles waving at well-wishers, in his first public outing since treatment.
5 February: The Palace announces that the King has been diagnosed with a “form of cancer” discovered during his recent treatment. The type of cancer has not been revealed, but the Palace says it’s not of the prostate and the King has started “regular treatment”.