St George is not only patron saint of England but has important connections to Greece, Moscow and Ethiopia all of which have flags or coats of arms showing George, on horseback, slaying the dragon.
The cross of St. George also features in Aragon, Catalonia, Genoa, Malta and Georgia.
I believe St George was brought to England via the first Crusaders,and it was they that started the veneration of St George.In fact they wore his emblem,a red cross on a white ground,on their tunics when they went into battle.
Historian