The Queen's Official Birthday (sometimes known as "the Queen's Birthday") is the day on which the birthday of the monarch of the United Kingdom and the Commonwealth Realms is officially celebrated rather than the actual day of the current monarch's birthday. The exact date of the celebration varies from country to country, and only marks the real birthday of a sovereign by coincidence (the current monarch, Elizabeth II, was born on 21 April 1926). Most Commonwealth Realms release a Birthday Honours List at this time.
It has been celebrated in the United Kingdom with the Queen's Birthday Parade (which includes Trooping the colour ceremonies) since 1748. In the UK there is no public holiday for it and King Edward VII (1901–10)[verification needed] moved it to the 1st, 2nd, or (rarely) 3rd Saturday in June in the hope of better weather. It might be said that the Monarch's official birthday is only this date as the Monarch declared it, and others have kept it, whereas the celebration of the Queen's birthday elsewhere is the name of a public holiday, sometimes renamed.
(... from Wikipedia on 2010-08-28 03:23:42 )