The Queen has two birthdays – her real one – in April, as she was born on 21 April 1926. Then a second one – the official celebration – on the second Saturday of June.
The convention of an official monarch’s birthday has been in place since 1748, during the reign of King George II.
George’s birthday fell in November, but he decided to change it so he could mark the occasion with a large-scale public celebration during the warmer months.
He made the decision to combine his celebration with Trooping the Colour, an annual military parade in the summer.
The Queen initially marked her “official” birthday on the second Thursday of June, the same day as her father, King George VI.
However, she changed it to its current position – the second Saturday of June – in 1959, seven years into her reign.
Technically, she actually has a few more birthdays, with some Commonwealth nations celebrating at different times.