Wikipedia tells us that East Anglia is generally considered to be Norfolk, Suffolk and Cambridgeshire, and that the shield of three golden crowns, placed two above one, on a blue background has been used as its symbol for centuries, dating back to the Wuffingas dynasty that ruled the area in Anglo-Saxon times. The flag as shown here, with the shield superimposed on the cross of St George, was adopted much more recently though, in 1902, by the London Society of East Anglians (itself only established in 1896).
Fascinating, yes? Well, no... especially when you consider that in all my years of coming to East Anglia, holidaying, studying, visiting, living, working, in all that time I've never seen the flag in use anywhere, ever. The three crowns on a blue shield, yes, sure. But the whole flag...? Never. Maybe I've been walking around with my eyes closed the whole time...
Here's an appropriate, and brilliant, song.

