While her Majesty traditionally celebrates her special day in private, she usually attends the annual Easter Sunday church service at St George’s Chapel in Windsor, with other members of the Royal Family.
There’s also her Birthday Parade, known as Trooping the Colour, which takes in June, but why does the Queen have two birthdays?
It all comes down to the weather.
Official celebrations to mark the Sovereigns’ birthday have often been held on a day other than the actual birthday, particularly when the actual birthday has not been in the summer.
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The Queen’s great grandfather King Edward VII, for example, was born on 9 November 1841, but his official birthday was always marked in May or June when there was a greater likelihood of good weather for the Trooping the Colour parade. The tradition is believed to date back to 1748, during King George II’s reign.
So while Her Majesty’s actual birthday is on 21 April, her official one is usually the second Saturday in June.
This year’s parade is scheduled to take place on June 8, when the Queen is joined by other members of the Royal Family for a procession and a public appearance on the balcony of Buckingham Palace.
Prince Charles is expected to follow suit and have two birthdays when he becomes king, especially as his birthday is 14 November.