Red Cross of Saint George United Kingdom Flag

The national flag of the United Kingdom is the Union Jack, also known as the Union Flag. The current design of the Union Jack dates from the Act of Union 1801 which united the Kingdom of Great Britain and the Kingdom of Ireland (previously in personal union) to create the United Kingdom of Great Britain and Ireland.

The flag consists of the red cross of Saint George (patron saint of England), edged in white, superimposed on the Cross of St Patrick (patron saint of Ireland), which are superimposed on the Saltire of Saint Andrew (patron saint of Scotland). Wales is not represented in the Union Flag by Wales's patron saint, Saint David, as at the time the flag was designed Wales was part of the Kingdom of England. Source: Wikipedia

Early Days

The earliest form of the flag of Great Britain, developed in 1606 and used during the reigns of James I (1603–25) and Charles I (1625–49), displayed the red cross of England superimposed on the white cross of Scotland, with the blue field of the latter. Because in heraldry a red on blue is not considered permissible, the red cross had to be bordered with white, its own correct field.

During the Commonwealth and Protectorate period (1649–60), the Irish harp was incorporated in the flag, but it resumed its original form on the Restoration of Charles II in 1660. It continued in use until January 1, 1801, the effective date of the legislative union of Great Britain and Ireland. In order to incorporate the Cross of St. Patrick (a red diagonal cross on white) while preserving the individual entities of the three crosses, the heraldic advisers to the sovereign found an elegant solution.

The existing white Cross of St. Andrew was divided diagonally, with the red appearing below the white on the hoist half of the flag and above it on the fly half. To avoid having the red cross touch the blue background, which would be contrary to heraldic law, a fimbriation (narrow border) of white was added to the red cross. In the centre, a white fimbriation also separated the Cross of St. Patrick from the red Cross of St. George. Source: Britannica

More About The UK

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK or U.K.) or Britain, is a sovereign country located off the north­western coast of the European mainland. The United Kingdom includes the island of Great Britain, the north­eastern part of the island of Ireland, and many smaller islands. Northern Ireland shares a land border with the Republic of Ireland. Otherwise, the United Kingdom is surrounded by the Atlantic Ocean, with the North Sea to the east, the English Channel to the south and the Celtic Sea to the southwest, giving it the 12th-longest coastline in the world. The Irish Sea separates Great Britain and Ireland. The total area of the United Kingdom is 94,000 square miles or 240,000 square kilometers, for our British friends.