'We need to talk about the royals' bizarre initiation ritual for potential princesses.'

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A new It Girl royal is coming. Her name is Harriet Sperling, and she just got engaged to Princess Anne's son, Peter Phillips.

And you best believe Harriet is getting the full royal welcome!

Now that the news is out about her engagement, the NHS nurse has scored an invite to the super-exclusive summer holiday at the royals' estate in Scotland, where the whole family heads every year to relax and hang out together.

Think of it like your family's annual trip to a seaside caravan park… only it's nothing like that at all. Because a very unique "test" is waiting.

You see, it's at Balmoral Castle in Aberdeenshire, Scotland that the storied 'Balmoral Test' is waiting for would-be royals, potential princesses and those keen to charm their way into the royal inner circle.

Listen to Mamamia Out Loud's hosts discuss the 'Princess Test'. Post continues after podcast.

The Balmoral Test is an unofficial initiation that guests of the British Royal Family — especially new romantic partners — are said to undergo at Balmoral Castle in Scotland.

It's not a formal examination (well, technically) but rather a weekend-long assessment of one's ability to navigate royal life and etiquette… which is, umm super normal.

Guests are observed (again, super normal) on how they perform important life skills like shooting, hunting and fishing (what about the art of sending a stern email??), along with their conversational skills at dinner (aka no jokes about Prince Andrew allowed!), and their general ability to "fit in" with the family.

Passing this unspoken test is seen as the first step in gaining acceptance into the royal family.

Harriet Sperling and Peter Phillips are engaged, but their biggest test is still to come. Image: Getty.

Think is sounds wildly pretentious but very British? You bet.

The most famous royal to pass the Balmoral Test is none other than the "people's princess" Lady Diana.

In one episode of The Crown (aka the closest thing we have to a royal encyclopedic text), the character of Charles admits that Diana goddamn aced the test.

"She was a triumph. In the history of Balmoral, no one has ever passed the test with such flying colours," Charles tells the fictional Camilla Parker-Bowles.

This glowing, five-star review reflects the accounts from the time when a then-19-year-old Diana visited the Royal Family's Scottish estate in September 1980.

Tina Brown wrote in The Diana Chronicles that Diana was embraced after her Balmoral visit.

"The adjectives every witness applied enthusiastically to Diana in these early days of her romance with Charles were 'uncomplicated,' 'jolly,' and 'easygoing.' It was a big plus to Diana's cause that she appeared so happy tramping over sodden moors," she wrote.

Prince Charles and Princess Diana had their honeymoon in Balmoral (seems fun). Image: Getty.

Along with potential princesses, politicians were also invited to the castle. In the case of divisive former Prime Minister Margaret Thatcher, her annual visits to Balmoral Castle couldn't have gone worse. She even famously described the tradition as being in "purgatory".

As much as the late Queen Elizabeth and Prince Phillip enjoyed a weekend of country torment — Prince Phillip was apparently the barbecue king and Queenie made a mean salad — not everyone had fun following the enforced rules and etiquette.

"The very quirks and obscure family traditions which have accrued over the years can intimidate newcomers," Andrew Morton wrote in Princess Diana: Her Story in Her Own Words.

"'Don't sit there,' they chorus at an unfortunate guest foolish enough to try and sit in a chair in the drawing room which was last used by Queen Victoria."

Queen Elizabeth II, Prince Philip, Duke of Edinburgh with their two young children, Princess Anne and Prince Charles outside Balmoral Castle. Image: Getty.

The Balmoral Test is make or break for incoming royals.

"Those who successfully navigate the social minefield… are accepted by the royal family. The ones who fail vanish from royal favour as quickly as the Highland mists come and go," Morton continued.

This was not an experience that Princess Diana enjoyed.

"I panic a lot when I go up to Balmoral," she told Morton. 'It's my worst time, and I think: "How the hell am I going to get out of this?"'

She described the time spent at the Scottish castle as being surrounded by negative vibes.

"The first couple of days, I'm frightfully chirpy when I get up there and everything's wonderful. By the third day, they're sapping me again. There are so many negative atmospheres. That house sucks one dry," she said.

But hopefully, the tense vibe is improving for future princesses.

Kate Middleton, aka the Princess of Wales, visited Balmoral in the summer of 2009 and royal biographer Katie Nicholl claimed she had a slightly more relaxed treatment from the Queen.

'It's not easy being the Queen's favourite!' Image: Getty.

The Queen even permitted the future Duchess of Cambridge to bring her camera to the estate. "She went out of her way to make her feel welcome," Nicholl wrote in her book Kate: The Future Queen, even "giving her permission to take pictures at Balmoral — a true gift to a photographer".

Must be nice!

In case you were wondering (I know you were, you nosy diva!), yes, Meghan Markle has been to Balmoral.

Watch the trailer for the second season of With Love, Meghan. Post continued after video.

She and Prince Harry reportedly visited the Queen's Scottish estate in the summer of 2018, a few months after their wedding.

But this was her only trip to the Scottish castle. They have not visited in the years since because… well, awkward.

It's unclear whether the death of the Queen means the end of the test, as it sounded like the Monarch held tight control of the weekend's festivities.

"They call it the Queen's Balmoral Test, but I would call it more of a royal initiation," royal editor-at-large Omid Scobie said to Harper's BAZAAR.

This queenie apparently ran a tight ship! Image: Getty.

"If you've scored an invite, prepare to brush up on your royal protocol, have a wealth of talking points at the ready, an outfit for EVERY occasion (from hunting to black tie) and, most importantly, be on your best behaviour at all times.

"If you don't like the food, eat it anyway. If you don't like trampling through the Highlands in the wind and rain, tough… You are entering her space, and whatever she does, goes."

Will the current King and Queen bring with them new traditions, and perhaps, the end of the Balmoral Test for potential princesses?

In the case of Harriet Sperling, we really hope so.

Feature image: Getty.