The Prince of Wales shared a touching moment with the King during the coronation service, when he leaned in to kiss his father on the cheek.
In a break with tradition, William was the only blood prince to pay homage to Charles during the service.
It was his wife, the Princess of Wales, who appeared to perform most of the parental duties, allowing the prince to focus on his role inside Westminster Abbey.
The King gave a small smile to William, as his older son approached to clothe him with the Stole Royal – a golden priestly scarf.
Kneeling before the King, he said: “I, William, Prince of Wales, pledge my loyalty to you and faith and truth I will bear unto you, as your liege man of life and limb. So help me God.”
William appeared to avoid eye contact with his father through much of the homage.
He then kissed Charles on the cheek and the King was seen to say a few words to his elder son.
William later appeared more relaxed once in a carriage with the children after the service, and was seen smiling and waving at wellwishers.
The couple were late to the service and were forced to join the King’s procession through Westminster Abbey.
Later, on the balcony of Buckingham Palace, William made a remark as he leaned closer to Kate, prompting her to turn and smile.