Kate Middleton May Have Just Revealed Her Nickname For Father-In-Law Prince Charles: Report

Kate Middleton may have just revealed her sweet nickname for her father-in-law Prince Charles during their outing last week, according to a report.

Queen Elizabeth II, Prince Charles, Camilla Parker Bowles, Prince William and Middleton joined forces in welcoming the world leaders to the G7 summit Friday. In a video taken during their arrival, the Prince of Wales was seen turning around to chat with his daughter-in-law and son. The Duchess of Cambridge greeted him with a warm smile while saying, "Hello, Grandpa!" People reported.

The Duchess of Cambridge did not use Prince Charles' royal title. The outlet noted that she might have also called the Prince of Wales "Papa" because that's how Prince William and Prince Harry address their father.

Prince Charles has become a grandfather for the fifth time after the Duke and Duchess of Sussex welcomed their daughter, Lili, on June 4. Prince Charles' grandchildren before baby Lili included Prince George, Princess Charlotte, Prince Louis and Archie. Prince Harry and Markle named their second child Lilibet Diana Mountbatten-Windsor as a nod to the Queen and Princess Diana.

Lilibet is Her Majesty's nickname when she was a child. She allegedly couldn't pronounce her name and referred to herself as Lilibet. Her late husband, Prince Philip, also loved to call her using the moniker. In fact, the Queen signed her hand-written card for the Duke of Edinburgh at his memorial service with "Lilibet." Meanwhile, "Diana" was a tribute to Prince Harry's late mom, the Princess of Wales.

Prince Charles also called Lilibet's arrival "happy news." The heir apparent briefly mentioned it in his speech about the development of battery-powered vehicles when he toured a BMW Mini factory in the United Kingdom earlier this month.

"The development of technology like electric vehicles … is vital for maintaining the health of our world for future generations, something I am only too aware of today, having recently become a grandfather for the fifth time," Prince Charles said, according to ITV’s royal editor Chris Ship.

"Such happy news really does remind one of the necessity of continued innovation in this area — especially around sustainable battery technology — in view of the legacy we bequeath to our grandchildren," he added.