This year the event marked the 85th birthday of the Sovereign who has reigned over the country since 1952.
In the past colours, or flags, were carried, or "trooped", down the ranks so that it could be seen and recognised by the soldiers as they were used as rallying points in the confusion of fighting. In the 18th century, guards from the Royal palaces assembled daily on Horse Guards to 'troop the colours', and in 1748 it was announced that the parade would also mark the Sovereign's official birthday.