It’s not often we get a glimpse into the family lives of the royals, but when we do it is oh-so endearing.

Recently the Duke and Duchess of Cambridge, along with their three children – Prince George, 5, Princess Charlotte, 4, and one-year-old Prince Louis – attended the ‘Back to Nature’ garden, which Kate Middleton helped design and create, at the Chelsea Flower Show.

During the family’s appearance on Tuesday, Wills let slip the adorable nickname he calls his daughter.

In a video posted to the Kensington Palace Twitter a

“How would you give it out of 10? How many marks would you give it, with 10 being the highest?” the 36-year-old father says.

“Twenty!” George replies whilst enjoying the swinging seat in the garden.

“Twenty out of 10? That’s pretty good,” William said. “I think mummy’s done well.”

In the clip, William then seems to call over to his daughter, Charlotte, asking her to give him a push on the swing seat.

But it is the word he used to call the little princess over that has melted our hearts.

“Mignonette?” William says, to which Charlotte replies, “Yes?”

“Give me a push!” her dad asks.

The word ‘mignonette’ is a French saying which, in English, means ‘darling’ or ‘dainty’.

The prince may have been saying to Charlotte, “Been on it yet?”, but we’re hoping it’s the former as that nickname is just too adorable not to be true!

While Charlotte’s royal nickname is certainly sweet, there are other members of the royal family who don’t have as cute pet names.

Throughout his time at university in St. Andrews, Scotland, where Wills met Kate, in order to fly under the radar, the prince went by the name of ‘Steve’ – an interesting choice if you ask us.

Meanwhile the Mail on Sunday previously reported Prince Charles had a rather unusual nickname for daughter-in-law Meghan Markle.

The Prince of Wales apparently calls the Duchess of Sussex ‘Tungsten’, as he sees her as “tough and unbending just like the very strong metal”.

Even the Queen herself has a few nicknames, mainly from her husband Prince Philip.

The Duke of Edinburgh reportedly calls Her Majesty ‘darling’, ‘cabbage’ and the pet name she has had since she was a child, ‘Lilibet’.

It’s clear the royals just can’t get enough of nicknames.