Kate Middleton's adorable nickname for Prince Charles is the sweetest royal family secret we've heard for a while

Kate Middleton's lovely nickname for Prince Charles was revealed by a lip reader earlier this year—and it encapsulates Charle's close bond with the Cambridges perfectly. 

• Kate Middleton's lovely nickname for Prince Charles has been revealed by a lip reader. 
• The future King and his daughter-in-law were seen chatting as they arrived at the Eden Project in Cornwall for the G7 summit earlier this year and it gave a rare insight into their bond. 
• In other royal news, Kate and William's parenting habit that the Queen 'can't stand' has been revealed. 

Prince William, Kate Middleton, Prince Charles, Duchess Camilla and Her Majesty the Queen all paid a visit to the Eden Project in Cornwall back in June, as part of the G7 summit. 

During the special royal appearance, Kate is thought to have been captured using a lovely nickname for the eldest of Queen Elizabeth's children, Prince Charles. The Prince of Wales is, of course, grandfather to her and Prince William’s three children, Prince George, Princess Charlotte and Prince Louis, who live down the road from Charles' Clarence House home in London's Kensington Palace. 

A lip reading pro says that Kate referenced Prince Charles’ close relationship with the little Cambridges, while highlighting her own sweet friendship with the future King, using a touching name for him. 

Having analysed the moment the members of The Firm arrived at the pivotal event, a lip reader told Cornwall Live that Kate greeted Prince Charles by saying, “Hello Grandpa, how are you?”

This gives an adorable insight into what monarch-to-be Charles is known as to his closest family members, including his young grandchildren. 

Meanwhile, it was previously revealed that Prince William’s late mother Princess Diana is known similarly by his three little ones.

As the UK celebrated Mother’s Day in March of this year, Kate and William shared a poignant look at George, Charlotte and Louis’ cards made for their grandma, who died years before they were born, in 1997. 

The messages inside the handmade notes confirmed that, despite having never met her, the Cambridge kids refer to the late Princess of Wales as “Granny Diana”. 

“Dear Granny Diana, happy happy mothers day. I love you very much and think of you always. Sending lots of love from George,” the little prince, who is third in line to the throne, penned. 

Meanwhile, Princess Charlotte wrote some heartbreaking words, reminding the world of Diana’s absence in Prince William’s life. 

“Dear Granny Diana. I am thinking of you on mother’s day. I love you very much. Papa is missing you. Lots of love Charlotte,” she wrote.