The Queen, 92, celebrates her birthday today, 9 June, but many will recall she already honoured the occasion earlier this year on 21 April.
This is because the Queen has two birthdays: her actual birthday – the date she was born – on 21 April, and an official birthday later in the year, where the public can celebrate the monarch’s birthday.
How old is Queen Elizabeth? She is 92 years old – just under five years younger than her husband, Prince Philip, 96, whose actual birthday is tomorrow.
Today, her official birthday will be marked, as is tradition, with the Trooping of the Colour parade, also known as The Queen’s Birthday Parade – where British troops take part in a pageant in honour of the monarch.
Why does Queen Elizabeth’s birthday change every year?
Royal fans may observe the Queen’s official birthday date for 2018 is different compared to last year.
Her birthday was celebrated on Saturday 17 June in 2017, as opposed to June 9 this year.
It is usually celebrated on the second Saturday in June each year, according to the Royal.uk website.
The choice of a weekend day means the public are more likely to be able to celebrate it.
The Queen’s official birthday was originally celebrated on the second Thursday of June, the same day her father, King George VI, chose to celebrate his.
However, in 1959 she made a decision to change her official birthday to two days later on the second Saturday of June instead.
Last year broke the trend, with the Queen’s birthday celebrated on the third Saturday in June instead.
Why does the Queen have two birthdays?
The tradition goes back to King George II, the British monarch in 1748. He decided his actual birthday month – November – was too cold for a public celebration.
Therefore, he chose to move his official birthday to a day in June, when it would most likely be warmer.
Queen Elizabeth has followed suit, just as her father King George VI did before her.
Queen Elizabeth celebrated her birthday earlier this year on 21 April by attending a concert at the Royal Albert Hall, London.
The music concert, organised by the BBC, was attended by royals including Meghan Markle, 36, Prince Harry, 33, and Prince William, 35.
The star-studded line-up includes Sting, Kylie Minogue, Sir Tom Jones and Craig David.
Pictures of the Queen celebrating her birthday show the milestone occasion throughout the years.
The royal family will appear on the Buckingham Palace balcony later today to honour the monarch’s birthday.