Etiquette experts say he also made a faux pas by clinking his glass against the royal's, though she smiled throughout the festivities.
The first lady wore a Dolce & Gabbana dress with navy trim and a matching hat to visit Buckingham Palace.
Just two days after giving birth, Meghan Markle and husband, Prince Harry,introduced the world to their little one on Wednesday
According to The Sun, the 74-year-old has been keeping a low profile while residing in Rosarito, Mexico. However, he decided to share his congratulations for the Duke and Duchess of Sussex, as well as the entire royal family.
"How any woman does what they do is beyond comprehension," said the Duke of Sussex — and new father.
Meghan Markle is home awaiting the birth of her first child, while Prince William marked Anzac Day in New Zealand.
What will the Duke and Duchess of Sussex’s baby’s name be? Well, it’s a surprisingly complicated matter.