LONDON -- Prince William on Sunday shared a photograph showing him as a child with his father, King Charles III, to mark Father’s Day in the United Kingdom this year.

The heir to the British throne posted the image on X and wrote: “Happy Father’s Day, Pa. W.”

The photo shows William and the then-Prince of Wales outside with a ball at Charles’ feet.

William’s own children – George, Charlotte and Louis – shared a tribute to their father on their parents’ Instagram account that included a photograph of the four of them at the beach.

“We love you, Papa. Happy Father’s Day. G, C & L,” read the message from Prince George, Princess Charlotte, and Prince Louis.

The photo was taken by Catherine, Princess of Wales, according to the caption.

Father’s Day comes a day after the Princess of Wales attended her first public engagement since being diagnosed with cancer. The 42-year-old joined other British royals on the balcony of Buckingham Palace to celebrate the King’s birthday on Saturday.

King Charles is also being treated for an unspecified cancer. The monarch, 75, returned to his public duties in April while he continues to receive treatment.