It is fairly safe to say that once they are behind the doors of the royal palaces, the Windsors don’t address each other using their official titles.
Some of the nicknames they use have become known to the public during the years.
Future king Prince William has been given one of his by his loving mother Diana.
The People’s Princess used to call him ‘Wombat’, as he revealed in a 2007 interview.
Speaking to NBC’s Matt Lauer, he said: “It began when I was two.
“I’ve been rightfully told because I can’t remember back that far.
“But when we went to Australia with our parents, and the wombat, you know, that’s the local animal.
“So I just basically got called that.
“Not because I look like a wombat, or maybe I do.”
Members of the Royal Family use very cute nicknames to call each others
Nowadays, William is more commonly known to his friends as ‘Wills’.
His wife Kate had been given not one but two nicknames during her life as a non-royal.
Years before becoming the Duchess of Cambridge, she received the nickname ’Squeak’.
The moniker comes from her beloved pet, a guinea pig, which was called the same way.
While visiting her old school, the St Andrew’s School in Berkshire, she said: “I was nicknamed Squeak just like my guinea pig.
One of Kate Middleton’s nicknames as a child was ‘Squeak’
Some of Prince Harry’s friends call him ‘Potter’
“There was one called Pip and one called Squeak because my sister was called Pippa and I was Squeak.”
And years before meeting Prince William, she was also being called “princess-in-waiting” by her classmates because of her popularity at the Marlborough College.
The loved-up couple have also given nicknames to each others.
During a day out at the Chelsea Flower Show in 2016, the pair were overheard calling each other ‘darling’ and ‘babe’.
And in July 2013, just hours after the birth of their first son Prince George, Prince William was overheard calling his wife ‘poppet’.
Kate and William call each other ‘babe’ and ‘darling’
The Duchess of Sussex, Meghan Markle, was also given two nicknames in her younger years, one from her mother and one from her father.
On her now-shut down Instagram account, she once shared a picture of flowers, adding a big revelation in the caption: “My mum has always called me ‘flower’.
“Nickname since I was a little girl.”
On the other hand, it is well-known that her father, Thomas Markle Snr, calls her ‘Bean’.
In a post dated 2016, she dedicated a lengthy thought to her dad to celebrate Father’s Day, which she signed off writing: “I love you xo – Bean.”
Prince William’s friends call him ‘Wills’
Meanwhile her now husband Prince Harry was overheard referring to his then-finance as “Meg” at the Invictus Games in Toronto last year.
And Meghan likes to refer to Harry as ‘Haz’, her agent has previous revealed.
Her now husband, the Duke of Sussex, also has a very well-know nickname.
His friends used to refer him as ’Spike’.
While it isn’t clear why they referred to him with such a peculiar name, we know he used it for four years as a pseudonym on Facebook.
Meghan Markle’s father calls her ‘Bean’
His account, carrying the name and surname of ‘Spike Wells’ was shut down in 2012.
But it is less known that Prince Harry’s friends have also adopted another monicker for him.
After visiting the Warner Bros Studios in 2013, Harry’s friends started calling him ‘Potter’.
Canadian journalist Lisa LaFlamme explained: “The title that caught my eye was the same one the Prince’s communications director promptly put away – a picture book about Harry Potter.
Prince Philip calls the Queen ‘Cabbage’
“To his friends, ‘Potter’ is the Prince’s nickname but apparently not something Palace PR would want to distract from our interview.”
Even the Queen has been given more than a nickname.
As a little girl, she referred to herself as ‘Tillabet’.
Growing up, she became known as ‘Lilibet’ among her family and close friends.
But her husband, the Duke of Edinburgh, also called her ‘Cabbage’, according to the 2006 film The Queen, where the monarch is impersonated by Dame Helen Mirren.