The Royal Arms we see today have evolved over nine centuries, since Richard the Lionheart chose three lions to represent England. This symbol on the King's shield would immediately identify him in the midst of battle.
The full version of the Royal Coat of Arms is now used only by the Queen in her capacity as the Sovereign. In the version used by the government and consequently as the official coat of arms of the United Kingdom of Great Britain and Northern Ireland, the crown is shown resting directly on the shield, with the helm, crest and mantling not displayed (like in the black and white photo above).
Above is a coloured photograph of the Royal Coat of Arms. (Please note that the unicorn horn is missing. It may have fallen off.) The Royal Coat of arms was on display above a canopy sheltering the Queen during a special ceremony at Whitehall
The main element of the Arms is the shield which is divided into four quarters.