The Making of the Union Flag

St George - England

1194

England is represented by the flag of St. George.
In 1194 A.D., Richard I of England introduced the Cross of St. George, a red cross on a white ground, as the National Flag of England.

Wales, a province of England

1536

In 1536, under Henry VIII, an Act of Union was passed making Wales, in effect a province of England.

St Andrew - Scotland

1540

Scotland is represented by the flag of St. Andrew
After Queen Elizabeth I of England died in 1603, King James VI of Scotland inherited the English throne and became King James I of England. It was a Union of the Crowns.
Early in his reign James attempted to combine England and Scotland in a united kingdom of 'Great Britain'.
James defied them. On 20 October 1604 he proclaimed a new title for himself as 'King of Great Britain'.

The first Union Flag

1606

On 12 April 1606, the National Flags of Scotland and England were united for use at sea, thus making the first Union 'Jack'. Ashore however, the old flags of England and Scotland continued to be used by their respective countries. A royal decree declared that the ships of the Kingdom of Great Britain "shall bear on their maintops the red cross, commonly called St. George's cross, and the white cross, commonly called St. Andrew's cross."
English flag + Scottish flag

United Kingdom of Great Britain

1707

When the red cross of England was put onto the flag of Scotland, a white border was added.
On 28th July, 1707, during the reign of Queen Anne, this flag was by royal proclamation made the National flag of Great Britain, for use ashore and afloat.
The Act of Union of 1707, joined England and Scotland together, creating a single kingdom called 'United Kingdom of Great Britain'.
England Wales and Scotland were now united together under one monarch and one parliament.

Northern Ireland - St Patrick

1783

Ireland is represented by the cross of St. Patrick
(a diagonal red cross on a white background.) On 1 January 1801, Ireland was united with Great Britain and it became necessary to have a new National Flag in which Ireland was represented. The cross St Patrick was combined with the Union Flag of St George and St Andrew, to create the Union Flag that has been flown ever since.

The Union Flag

1801

The cross of St. Patrick was inserted so the position given to St. Andrew's Cross in one quarter was the same as that given to the Irish one in the diagonally opposite quarter; in heraldry this is known as "counterchanging"
The 'new' British flag is not symmetrical
England, Wales, Scotland and Ireland were now all joined together and called the United Kingdom of Great Britain and Ireland
The Union Flag consists of the three heraldic crosses of St George, St Andrew and St Patrick

Wales

1953

Why doesn't the Welsh dragon appear on the Union Flag?
The Welsh dragon does not appear on the flag because when the first Union Flag was created in 1606, Wales was already united with England from the 13th century. This meant that Wales a Principality instead of a Kingdom and as such could not be included.
In 1536, under Henry VIII, the Act of Union joined England and Wales officially.