From: "Phil Payne" 

> What are the differences?  I've been playing with an image of the flag
> and can't tell the difference when I rotate it 180 degrees.

http://en.wikipedia.org/wiki/Image:Flag_of_the_United_Kingdom.svg

Look at where the red and white diagonal crosses meet the flagstaff on the
left.  The white one is usually cited - broad where it meets the top and
narrow where it meets the bottom.  Critically - the broad white stripe that
meets the flagstaff must be at the bottomw.

--- BBBS/NT v4.01 Flag-5