King Charles III waves his top hat and shakes hands with guests at a Buckingham Palace garden party on Wednesday.
He is joined by his wife, Queen Camilla, for the first of two summer parties the Palace will host this year.
The King took a break from public-facing duties after announcing his cancer diagnosis in February. He has since returned to some public appearances while his cancer treatment continues.
Prince Harry is also in London on a flying visit from his home in California, but he will not meet the King. Harry's spokesman said the King's "full programme" prevented the two from meeting.