11/17/2017 11:29 EST | Updated 11/17/2017 11:30 EST

The Queen And Prince Philip Are Keeping It Casual For Their Platinum Wedding Anniversary

Seventy years, and still going strong.

Queen Elizabeth II and Prince Philip attend day 2 of Royal Ascot at Ascot Racecourse in June 2016.
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Queen Elizabeth II and Prince Philip attend day 2 of Royal Ascot at Ascot Racecourse in June 2016.

It's rare to hear of a couple celebrating their platinum wedding anniversary, but in the case of Queen Elizabeth II and Prince Philip, it's not only rare, but historic. Nov. 20 marks this milestone for the pair, making them the first royal couple to celebrate 70 years together, BBC News reports.

The couple tied the knot at Westminster Abbey in 1947. At that time, Princess Elizabeth was just 21 years old, while her groom, naval officer Lieutenant Philip Mountbatten, was 26.

Seven decades later, the royals are celebrating the only way they know how: by hosting an intimate family dinner at Windsor Castle.

Although parts of the castle are open to the public, the attraction's official website states that state apartments, as well as semi-state rooms, will be closed on Nov. 20. Hello! magazine speculates that this is likely to give the royals their privacy, as a number of royal family members are expected to attend.

The Queen and Prince Philip's four children — Prince Charles, 69, Princess Anne, 67, Prince Andrew, 57, and Prince Edward, 53 — will all be in attendance, as will the royal couple's older grandchildren, including Princes William and Harry, and Princesses Beatrice and Eugenie.

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(L-R) Queen Elizabeth II, Prince Philip, Duchess of Cambridge, Princess Charlotte, Prince George and Prince William look out from the balcony of Buckingham Palace in June 2017.

William's wife, the Duchess of Cambridge, and their children, four-year-old Prince George and two-year-old Princess Charlotte, are also likely to attend, but no word on whether or not Harry's girlfriend, Meghan Markle, will be at the festivities.

The private affair will be the only anniversary celebration for the Queen and Philip, as a Buckingham Palace spokesman confirmed to Reuters that there will be no public event.

The Queen and Prince Philip's love story is truly a remarkable one. The two met in 1934, and again in 1937. After meeting again at Royal Naval College in Dartmouth in 1939 when Princess Elizabeth was just 13, the two began exchanging letters and their relationship blossomed.

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Princess Elizabeth and the Duke of Edinburgh arm in arm in Nov. 1947.

Shortly after the Queen turned 21, the two became officially engaged, and they tied the knot on Nov. 20, 1947.

Although their love story sounds like something straight out of a fairy tale, their relationship and marriage didn't come without challenges, as Netflix's popular show "The Crown" — which chronicles the Queen's life — alludes to.

In fact, the Queen married Philip against her family's wishes. At the time, Elizabeth's family was not only concerned about Philip's lack of money, but of his foreign-born status. (Although a British citizen, he was the Prince of Greece and Denmark.) But the Queen chose to follow her heart anyway.

AFP/Getty Images
Queen Elizabeth II accompanied by Prince Philip waves to the crowd in June 1953 after being crowned solemnly at Westminter Abbey.

Additionally, their marriage experienced strains after Elizabeth ascended to the throne in 1952, following the sudden death of her father, King George VI. One issue that caused a significant rift was Elizabeth's decision to keep her father's name, Windsor, instead of adopting Mountbatten as the royal family name.

But despite this and other challenges, Philip has always stood by the Queen. "One of the secrets of this very, very long marriage, and it's an incredibly impressive anniversary, is the fact Prince Philip has always seen it as his main duty to support the queen, to help her in whatever way he can," royal historian Hugo Vickers told Reuters.

"He is the only person who can actually tell the Queen absolutely straight what he thinks, and if he thinks some idea is ridiculous he will say so in whatever language he chooses to use."

Tim Graham/Getty Images
Queen Elizabeth II and Prince Philip in 2007 marking their diamond wedding anniversary.

The Queen previously confirmed her husband's loyal and supportive nature. In 1997, on their golden wedding anniversary, she said, "He is someone who doesn't take easily to compliments. But he has, quite simply, been my strength and stay all these years. I and his whole family, in this and many other countries, owe him a debt greater than he would ever claim or we shall ever know."

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