Charles, William and Kate made a surprise appearance on Friday afternoon.
The King and the Prince and Princess of Wales have greeted well-wishers on the Mall on the eve of the coronation.
Charles, William and Kate made the surprise appearance to the delight of huge crowds gathered outside Buckingham Palace.
The trio took time to shake hands with members of the public as people cheered, took selfies and sang God Save the King.
Earlier, the King took part a final coronation rehearsal at Westminster Abbey, where a 2,300-strong coronation congregation, and a television audience likely to be in the tens of millions, will watch him being crowned on Saturday.