Kate Middleton lovingly calls her father-in-law Prince Charles 'Grandpa'

Kate Middleton revealed nickname for her father-in-law Prince Charles when they, along with their spouses, joined Queen Elizabeth in welcoming world leaders to the G-7 summit.

In a video from their arrival, Prince Charles - who recently became a grandfather for the fifth time - turns around to chat with his son Prince William and daughter-in-law Kate Middleton.

The Duchess appeared to greet the prince of Wales with a warm smile and the words at the event, "Hello, Grandpa!" rather than his more formal title.

The 39-year-old royal also calls the 72-year-old prince "Papa", the name his sons Prince William and Prince Harry use for him.

Undoubtedly, Kate Middleton is a jewel in the monarchy's crown and proving a force for good in the latest royal row. 

It has also been reported that the Duke of Sussex texted his sister-in-law to share the happy news about his second child instead of Prince William. Royal experts hail Kate's growing influence as the 'glue' holding the  family together.