The late Queen developed a close bond with her daughter-in-law Camilla. However, she chose not to attend a birthday party held in Camilla's honor before her marriage to then-Prince Charles.
In July 1997, Charles hosted an extravagant birthday celebration for Camilla at Highgrove to mark her milestone 50th birthday.
This event came just a year after the finalization of Charles and Princess Diana's divorce and was the first joint occasion for Charles and Camilla.
According to the Guardian at the time, "It has been interpreted as an attempt to bring their relationship into the open."
However, the Queen and Prince Philip did not attend the party on July 18, 1997, nor did any of Charles' siblings, or Princess Margaret.
It is unclear if Charles tried to convince his mother to go to the party, as depicted in Netflix's 'The Crown', and the 80-person guest list has remained largely secret. It's thought that the invitees enjoyed canapés, a five-course meal, cake, and even a spot of dancing.
At the time, Princess Diana was on holiday in the South of France with young Prince William and Prince Harry.
Some eight years after the party, Charles and Camilla were married in a civil ceremony. Again, the Queen and Philip were not in attendance - but were wholly supportive of the happy newlyweds.
Charles and Camilla's wedding in 2005 was held in two parts; the official marriage at the Guildhall, followed by a Service of Prayer and Dedication at St. George's Chapel afterwards. A reception was then held for the couple in Windsor Castle.
As the head of the Church of England, the Queen ultimately decided that it was not appropriate for her to be at the wedding of two people who had each divorced their previous partners. But she went out of her way to help celebrate their special day.
Former royal butler Grant Harrold worked within Charles' household for seven years between 2004 and 2011, and was a guest at the ceremony in Windsor on April 9, 2005.
Speaking to Guides for Brides, he revealed that the late monarch actually organised important wedding details on the day, from the flowers, to Charles and Camilla's wedding rings. And she even gave a comical speech at the newlywed couple's reception.
Grant said: "The biggest misconception about the wedding is that the Queen didn't enjoy it or wasn't supportive, it's complete nonsense. There was talk about whether she would attend the service but her appearance at the reception was a joyful one.
"Her attendance and speech would have been seen as an olive branch to Charles and Camilla - her blessing of the marriage. The royals don't do things lightly and she would have not attended if she hadn't been happy to.
"I remember walking to St George's Hall for the reception, where they had drinks. The Queen had not attended the actual service but she gave a speech at the reception, which was seen as a big sign of her approval to the marriage.
"The Queen was amazing at the wedding, she gave a very funny speech, she was really happy as was Prince Philip. I can't remember her exact words but she was funny. She compared their relationship to a Grand National horse race. She was a great comedian and had a way with words."
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