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"Wishing Her Majesty The Queen a very happy 94th birthday today!" the couple captioned a photo of the pair on a stroll with the queen on Instagram.
About an hour later, the queen's supporters were treated to a clip compiled of home videos of Her Majesty throughout her formative years. The one-minute video was posted to the royal family's official Instagram account and features the queen as a young toddler playing with her late sister, Princess Margaret. Her love of animals is also on display as the rare footage shows adorable clips of her cuddling with puppies and birds.
"Happy Birthday, Your Majesty! Thank you for your messages today, on The Queen's 94th birthday. In this private footage from the @royalcollectiontrust, we see The Queen (then Princess Elizabeth) playing with her family, including her younger sister Princess Margaret," the account captioned the video.
"Head of the Commonwealth, Head of the Armed Forces, Head of State in 16 countries and the longest reigning Monarch in British History. Wife, mother, grandmother and great-grandmother. Happy birthday, Your Majesty!" the post continues.
"To those of you also celebrating your birthdays today at home, with or without your loved ones - we send you many happy returns."
Queen Elizabeth's granddaughter Princess Eugenie also acknowledged the reigning monarch's celebratory day.
"May today bring joy in a time when families can't be together celebrating with one another. All my love," Eugenie wrote.
The Clarence House, the office for the queen's eldest son, Prince Charles, also paid tribute to the queen's 94th birthday with a slideshow of photographs showing the mother-son duo over the years.
As of Tuesday afternoon, Meghan Markle and Prince Harry had yet to publicly share their birthday wishes for the queen. Although it's possible the couple will not make a statement following the shuttering of their Sussex Royal Instagram account.
The queen's birthday comes at a somber time in history due to the coronavirus pandemic, which shuttered the queen's annual birthday gun salute, as well as her birthday parade, also known as the Troop of Colour, that was cancelled.
Last month, Buckingham Palace confirmed in a statement that the queen departed for Windsor Castle ahead of the Easter holiday due to the COVID-19 crisis. It is likely she is still staying there with her husband, Prince Philip.