The St George’s Cross was adopted as the flag of England in the 16th century, although it has represented England since the Crusades. The red cross on white background also represents the official arms of the Most Noble Order of the Garter.
The Cross of St George has been the official emblem of England since 1188, and consists of a red cross on a white background. The symbol is associated with Saint George, a Greek-born Roman army officer, who has been venerated as a Christian martyr. He has been immortalized in the story of Saint George and the Dragon, and is the patron saint of England, as well as Georgia, Aragon, Genoa, and Barcelona.
The origins of the flag of England date back to the beginning of the Crusades, when the Pope declared that English crusaders would wear a different emblem than crusaders of other nations. The English wore a white cross on a red background, while the French wore a red cross on a white background. In 1188 however, the French king Philip II of France agreed to swap the colours with the English, resulting in the adoption of the St George’s colours for the English.
So, as with William Shakespeare, who enjoyed huge success as a playright in the 16th Century, it was also the century that saw the adoption of the St George’s Cross as the flag of England under the Tudors.