File:UKFlag.png

Summary
Description: The Flag of the United Kingdom of Great Britain and Northern Ireland, also known as the or. The current design dates from the Union of Great Britain and Ireland in 1801 - the flag consists of the red cross of Saint George (patron saint of England), edged in white, superimposed on the (patron saint of Ireland), which are superimposed on the  (patron saint of Scotland).

Source:

Purpose: To illustrate what the flag in question looks like on articles, as well as representing the flag's respective nation/faction in the relevant sections/articles