What is the history behind Queen Elizabeth have two birthday celebrations? Is this unique to her or a tradition among previous British monarchs?

Two? Try 6 The real one, the official one, one in Canada, one in most of Australia, one in Western Australia, and on in New Zealand

Anyhow, the BBC has some information on it. It seems she's not the first - King Edward VII started it by celebrating his November birthday in the summer.

"Harold Brooks-Baker, pubishing director at Burke's Peerage, thinks the whole idea of official birthdays is an out-of-date oddity..."

Some would say the same thing about monarchies. Thanks for the link.

What the link doesn't make clear is what reason there was for the late King having an official birthday. He was born in November. That is no time to be holding an event with pageantry, an event which you a lot of people will want to attend. It's bad enough having Armistice Day in November weather. Wet, cold, miserable and gloomy are suitable conditions in which to remember the deaths of millions in cold, wet, miserable, gloomy, trench warfare, but not ideal for a birthday celebration So his true birthday was celebrated privately and with minimal formal fuss and an official birthday was set to be celebrated at a more agreeable time of year.

[Some of us who were born at Christmas time would like to have an official birthday too. At least then we'd have a day for ourselves ]