How true is the ‘Balmoral Test’ in ‘The Crown’? The unwritten rules that govern the Queen’s Scottish hideaway

Princess Diana passed with flying colours, while former British Prime Minister Margaret Thatcher dubbed it ‘purgatory’

Making a happy group on the lawns at Balmoral, are the Queen, the Duke of Edinburgh and their three children Princess Anne, Prince Charles and baby Prince Andrew, on his father's knees. Getty Images

As season four of Netflix's The Crown debuts to rave reviews (and rumoured royal displeasure), one episode in particular has captured the global imagination.

Titled The Balmoral Test, the second episode in the latest season of the hit show focuses on Balmoral Castle, Queen Elizabeth II's 20,234 hectare acre estate in Aberdeenshire, Scotland, where the monarch heads for two months every summer on holiday.

Visited by British prime ministers and various heads of state over the years, the episode follows two very different women – Diana Spencer and Margaret Thatcher – as they navigate the unwritten rules and tests that are said to lie in wait for anyone who visits.

And the question everyone is asking is: is the Balmoral Test real?

In a word: Yes.

"Ever since Queen Victoria bought the estate in 1848, it has had a special place in the affections of the royal family," wrote biographer Andrew Morton in his book Diana: Her True Story – in Her Own Words.

“However, the very quirks and obscure family traditions which have accrued over the years can intimidate newcomers. ‘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. Those who successfully navigate this social minefield, popularly known as the Balmoral test, are accepted by the royal family.”

Obscure rules and unwritten regulations

"I think Granny is the most happy there. I think she really, really loves the Highlands," revealed Princess Eugenie in the documentary Our Queen At Ninety. And former royal photographer Patrick Anson, also known as Lord Lichfield, who died in 2005, said back in 1972 that at Balmoral, the royal family "act as normal people – to a point".

According to The Telegraph, the unspoken set of social rules and codes include knowing what to wear and when, adhering to royal protocol – who to bow to first, second, third and so on – participating in parlour games, knowing where to sit (and where not to sit), and joining in the many outdoor pursuits come rain or shine.

According to the Queen’s royal biographer, Ben Pimlott, Thatcher referred to trips to Balmoral as “purgatory”, calling the castle and its upper-class environment “a different world".

In The Balmoral Test, Thatcher (played by Gillian Anderson) and her husband, Dennis (Stephen Boxer), are seen puzzling over the separate bedrooms, being upbraided by Princess Margaret for saying "I beg your pardon" ("Say 'what'!" she snaps), and are left wondering what they should wear for "drinks at six, dinner at eight".

Deciding to dress up for drinks, they enter the parlour to find the royal family and friends still in their casual clothes.

Thatcher's biographer, Charles Moore told The Telegraph that the "broad impression" has "the ring of truth".

How Princess Diana passed the test

"The ones who fail (the Balmoral Test) vanish from royal favour as quickly as the Highland mists come and go," Morton wrote in his book. That fate, however, did not befall the young Diana Spencer, who enjoyed her third date with Prince Charles at the castle.

"She was a triumph. In the history of Balmoral, no one has ever passed the test with such flying colours," Charles tells Camilla in the show. And biographers agree that upper class Diana successfully navigated the complex social rules that govern the estate.

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

However, Diana's enjoyment of the castle is said not to have lasted very long. After their 1981 wedding, Charles and Diana honeymooned at Balmoral, and the Princess of Wales later revealed in Diana: Her True Story: "Charles used to want to go for long walks around Balmoral the whole time we were on our honeymoon. His idea of enjoyment would be to sit on top of the highest hill at Balmoral."