Incorporation into the Union Flag

The Flag of England is one of the key components of the Union Flag. The Union Flag has been used in a variety of forms since 1606, when the flags of the Kingdom of Scotland and Kingdom of England were first merged to symbolise the Union of the Crowns. (The Union of the Crowns having occurred in 1603). In Scotland, and in particular on Scottish vessels at sea, historical evidence suggests that a separate design of Union Flag was flown to that used in England. However, following the Acts of Union of 1707, which united the Kingdom of Scotland and the Kingdom of England, the 'English' version of the Union Flag was adopted as the official flag of the unified Kingdom of Great Britain.
From 1801, in order to symbolise the union of the Kingdom of Great Britain with the Kingdom of Ireland, a new design which included the St Patrick's Cross was adopted for the flag of the United Kingdom of Great Britain and Ireland. This new design, having remained unchanged following the partition of Ireland in 1921 and creation of the Irish Free State and Northern Ireland, continues to be used as the flag of the United Kingdom of Great Britain and Northern Ireland.