Britain's Queen Elizabeth II travels in an open carriage from Buckingham Palace for the trooping of the colour ceremony to honour her official birthday June 16, 2001. Trooping the Colour has honoured the sovereign's official birthday since the 17th century and dates back to the earliest times of armed conflict, when each leader needed his own flag or colours to stand out clearly amid the smoke and dust of battle which led to regular trooping allowing soldiers to recognise the colours around which they should rally.

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