Fact-Checking The Crown : How Much of Season 4 Is True — and How Much Is Fiction?

Warning: Spoilers ahead!

The highly anticipated fourth season of The Crown drops Sunday, Nov. 15 on Netflix, and fans are in for a royal treat. After three drama-filled seasons, the hit show is about to embark on a new era: the Diana years.

In addition to introducing Emma Corrin as a young Princess Diana, a new political figure enters the scene in the form of Margaret Thatcher, played by Gillian Anderson. And Olivia Colman returns as Queen Elizabeth for one of the most difficult periods in her reign: the tumultuous '80s.

As the fourth season begins, the perennial question of how much is true remains. Here's a breakdown of some of the biggest plot points, including what's based on truth and what's just for show.

Did Prince Charles date Diana’s older sister Sarah first?

Yes. We're first introduced to Diana Spencer via her older sister Lady Sarah in the first episode. Lady Sarah was among a series of girlfriends who filled the gossip columns as Charles turned 30 – an age his biographer Jonathan Dimbleby said he had “unwisely intimated was an appropriate age for marriage.” In fact, he dated her around 1977, when he was approaching that key age. That was the first time he had met the then Lady Diana Spencer – who struck him as “a very jolly and amusing and attractive 16-year-old . . . great fun, and bouncy and full of life and everything,” he said at their engagement interview in 1981.

Did Lord Mountbatten send Charles a letter before he died about finding an appropriate wife?

He might not have sent a letter to Charles on the eve of his death, which is depicted in episode one, but Mountbatten certainly dispatched copious amounts of advice to his great-nephew. Their relationship was more one of a grandfather-grandson, and mentor Mountbatten took it upon himself to counsel the prince in matters of the heart. He encouraged him to “sow his wild oats” before settling down and he advised a perfect bride would be one with no past and was young enough to be “molded to the role as wife and mother,” as Dimbleby put it.

Did Diana win the royal family over during her first visit to Balmoral Castle in Scotland?

Passing the so-called Balmoral Test has been important for all kinds of visitors, not just prospective royal wives. Politicians and their spouses have been among those scrutinized by the royals and their retinue. Diana passed with flying colors, as shown in episode two, winning over Charles’ friends during that first holiday in late summer/early fall 1980. Patty Palmer-Tomkinson noted her boundless energy as she fell in and out of the boggy, muddy ground while they were out stalking. Diana’s sister Jane had a house on the estate and had stayed there and was “no stranger to Scotland,” says Ingrid Seward, author of Prince Philip Revealed, and was happy to be “up early to be ready and out with the guns.” Philip also took her under his wing in those early days. “He always likes an outsider, having been one himself,” she adds.

Was Diana allowed to choose her own engagement ring?

Yes. A tray of jewels was presented to Diana after the engagement. In Andrew Morton’s Diana: Her True Story – In Her Own Words, she said there had been a cover story explaining the arrival of the jewelry to the palace so word didn't get out ahead of time. Instead, staffers were told Prince Andrew was getting a special signet ring for his upcoming 21st birthday. Diana was shown several options: “Along come these sapphires. I mean nuggets! I suppose I chose it. We all chipped in. The Queen paid for it,” her taped interviews for Morton revealed.

Did Camilla initially try to befriend Diana before the wedding?

Yes. Throughout the courtship, there had been evidence of Camilla’s closeness to the Prince of Wales. Diana and Charles would stay with Camilla and her husband Andrew Parker Bowles for weekends, and they would also be in attendance at Buckingham Palace evening dinners as Charles wooed Diana.

When Diana moved into Clarence House, the then home of the Queen Mother, on the eve of her engagement announcement, there was a letter from Camilla waiting for her, asking Charles’s fiancée out to lunch. But for Diana, any potential friendship was short-lived. As the wedding day of July 1981 drew near, she found out that Charles had commissioned a special bracelet with the intertwined letters of G and F inscribed on it – for their the nicknames they had for each other: Gladys and Fred. This painful moment plays out in the show's third episode.

Did Princess Diana really roller skate in the palace?

While it hasn't been confirmed whether Princess Diana did, in fact, roller-skate through Buckingham Palace while listening to Duran Duran's "Girls on Film" on her Walkman (like she does in the show), she was known to be a roller-skating pop music fan. She also used to relax while rollerblading in Kensington Gardens.

At least one person believes the carefree moment in season 4 is rooted in fact. Emma Corrin, who plays Diana, told Sky News: "I think she [really] did do that. "Do you know what, it was that kind of thing, it was the roller skating, the sense of fun that she obviously had before she became royal and that she kind of maintained, that I think was quite rare."

"Roller-skating through Buckingham Palace is a great example," she added. "Also, the dancing, her dancing and how much that meant to her, and how she used that as a kind of form of expression. I really loved discovering that."

Did Princess Diana have an eating disorder?

Princess Diana herself confirmed that she struggled with "rampant bulimia" in a November 1995 interview with BBC1's Panorama — and her eating disorder is depicted throughout the fourth season.

"It was a symptom of what was going on in my marriage. I was crying out for help, but giving the wrong signals, and people were using my bulimia as a coat on a hanger. They decided that was the problem: Diana was unstable," she said, adding: "The cause was the situation where my husband and I had to keep everything together because we didn't want to disappoint the public, and yet obviously there was a lot of anxiety going on within our four walls."

Did Princess Margaret try to stop Prince Charles and Princess Diana’s wedding?

There's no evidence that Margaret spoke up against the ill-fated union ahead of the wedding, as she does in episode three. In fact, Helena Bonham Carter said she came up with the idea that her character Princess Margaret should object to Prince Charles and Princess Diana's marriage.

Bonham Carter shared in a press conference that in the Netflix hit's fictionalized account, "it becomes very clear before the marriage that there are big problems," yet the family encourages Prince Charles to go through with it.

"I like to credit myself with an idea. I said, 'Hang on, I'm not really part of this.' They all looked at me," the actress recalled. "Maybe I've totally imagined this, but I said, 'Well, I'm not going to be encouraging an interference with a marriage when — back when I was Vanessa Kirby back in season 1 — my whole life was destroyed by my sister interfering with a marriage.' "

Is Princess Anne the favorite child of Prince Philip? And Prince Andrew the Queen’s favorite?

One of the season's most humorous moments is when the Queen meets with each of her children to figure out her favorite. In real life, Princess Anne and her father certainly have a close bond and share many of the same traits, including a strong work ethic and a love of horses. Eileen Parker, the wife of Philip's close friend Mike Parker, previously told the Daily Mail: "[Philip] always had more fun with Anne. Charles is more like the Queen, while Anne is very like Prince Philip."

Meanwhile, the Queen has always had a particular fondness for Prince Andrew. When Prince Charles and Princess Anne were born, the monarch wasn't able to spend lots of time with them, so they were raised primarily by nannies. She was more settled in her role when Andrew was born, allowing her to spend more time with him and develop a special relationship.

Was there really a palace intruder who confronted the Queen in her bedroom?

Yes! In one of the royal family's worst security breaches in history, British man Michael Fagan entered Queen Elizabeth's Buckingham Palace bedroom in 1982. In a 2012 interview with The Independent on Sunday, Fagan recalled being in the monarch's bedroom. "I was scareder than I'd ever been in my life," he said. "Then she speaks and it's like the finest glass you can imagine breaking: 'Wawrt are you doing here?!' "

While it was reported that the two had a long conversation, Fagan said: "Nah! She went past me and ran out of the room; her little bare feet running across the floor."

Did Queen Elizabeth and Princess Margaret have secret cousins who were hidden away in a mental institution?

Yes. One of the biggest bombshells of the season comes in the seventh episode with the discovery of the royal sisters' secret cousins. Two of the Queen’s first cousins and three of their second cousins had been secretly admitted to the Royal Earlswood Asylum for Mental Defectives in Surrey in 1941 by their parents, who were the older brother and sister-in-law of the Queen Mother, Elizabeth Bowes-Lyon. The girls were born during a time when children with disabilities were a family’s shameful secret.

The two first cousins were listed as dead in the 1963 edition of Burke’s Peerage, a guide to the British aristocracy, even though they were both alive at the time. Nerissa Bowes-Lyon didn't die until 1986 at the age of 66, while Katherine Bowes-Lyon died in 2014 at the age of 87. Mentally, the women were young children and could not speak. The shocking story was uncovered by the media soon after Nerissa’s death. The Queen never commented on the revelation, with the palace citing it as a private matter for the Bowes-Lyon family.

Did Queen Elizabeth and Margaret Thatcher have a rift?

The storyline in season four addresses some of the real-life tensions between the Queen and her first female prime minister, Margaret Thatcher, who served from 1979 to 1990. Though they were similar in age (just months apart) and both held powerful positions in a male-dominated world, they did not see eye-to-eye on many issues. They often held conflicting views, including a disagreement over sanctions against apartheid in South Africa (Thatcher in opposition to sanctions, and the Queen in support).

The Queen also struggled with how divided Britain seemed soon after Thatcher's arrival, with a devastating recession, riots and homelessness. In 1986, the Sunday Times ran a front-page story claiming that the Queen privately felt Thatcher’s approach to be “uncaring, confrontational and socially divisive.” The source was reportedly the palace press secretary, Michael Shea, but the Queen was said to be mortified by the headline-making story.

Despite their differences, their relationship softened over the years. The Queen honored Thatcher with The Order of Merit just two weeks after she resigned. Thatcher's 2013 funeral was also the first PM's funeral attended by the Queen since Winston Churchill.

Did Princess Diana surprise Charles with a dance to "Uptown Girl" at the London Opera House?

Yes. And the December 1985 dance was all Diana's idea! The princess, who loved ballet and took lessons at Kensington Palace, contacted ballet star Wayne Sleep about choreographing a dance as a special surprise for her husband. The duo met in a rehearsal studio in west London. "She said, 'I’ve got the music, it’s Billy Joel’s 'Uptown Girl' and I’m your uptown girl. And she was my uptown girl. She always signed little cards to me like that," Sleep said in PEOPLE's The Story of Diana.

"We just clicked — we had the same humor. I had to lift her right across the stage at one point. Suddenly, I realized what if I drop the monarchy? You know, I was more nervous than she was," he added.

Despite the delight from the crowd at the Royal Opera House, Charles was said to be less than thrilled with the three-minute number, which included jazz, ballet and a kick line.

“It was a present which slightly backfired," royal expert Richard Kay said. “She did it as a tribute to Charles. Charles wasn’t terribly impressed. He thought she was showing off.”

Was Prince Charles feared dead after an avalanche while skiing at a Swiss resort?

Though never feared dead by the royal family, Charles was involved in a deadly avalanche that took the life of his friend, Major Hugh Lindsay, at the Swiss resort of Klosters in 1988. Prince Charles, who was not hurt in the incident, reportedly joined other members of the party in a frantic effort to dig out Lindsay. Witnesses said the prince looked distraught, and one said he was crying as a helicopter arrived to pick him up. While Diana is shown receiving the news back in London in episode nine, in actuality, she was on the ski trip with her husband. She wasn't on the slopes that day, however. She had stayed behind at the royals' rented chalet with Prince Andrew's wife Sarah Ferguson, who was pregnant at the time.

Did Prince Philip have a heart-to-heart with Princess Diana over Christmas at Sandringham about her unhappiness?

While it's not known if an intimate conversation between the two actually occurred at the Queen's Sandringham Estate (as is depicted in the season's final episode), Philip, whom Diana affectionately called "Pa," was an early ally of the princess's.

Tobias Menzies, who portrays Queen Elizabeth's husband in The Crown, discussed how Prince Philip was initially taken with his daughter-in-law.

"I guess there are some similarities in that, you know, it's another outsider, a position that he obviously has been in. Maybe he has some kind of appreciation for the challenges that she's going through," Menzies said ahead of the season four premiere.

Philip and Diana often communicated via handwritten letters, with the Duke of Edinburgh offering his support in helping Diana save her marriage, but ultimately his loyalty remained to the Crown.