The King has been seen in public for the first time since his cancer diagnosis as he left Clarence House the day after starting his treatment.
Charles and the Queen were driven away from their London residence to Buckingham Palace, where they were believed to have been flown to Sandringham in Norfolk.
The Duke of Sussex is said to have been reunited with the King after Harry made a transatlantic dash to be with Charles following his cancer diagnosis.
Harry arrived in London from California on Tuesday afternoon less than 24 hours after the shock news was announced to the nation by Buckingham Palace.
The brief reunion between Charles and his youngest son has raised hopes the pair will be reconciled despite their troubled relationship.
The King, 75, who began treatment for the disease on Monday, has postponed all public-facing duties, but is continuing with behind-the-scenes work on his red boxes of state papers.
