The Queen celebrates her 91st birthday today and is expected to spend the anniversary privately. In Hyde Park at midday, 41 volleys in honour of her birthday will be fired by the King's Troop Royal Horse Artillery. Then an hour later the Honourable Artillery Company will fire a 62-gun salute at the Tower of London - an extra 21 for the City of London.
Princess Elizabeth Alexandra Mary was born at 2.40am on April 21 1926. Test how well you know the Queen in our quiz below.