I would lend support to the welsh connection, I am from the FOD and my wife is from Wales, and it was her family that introduced me to the term jibbons. My family always called them spring onions.

I also found this minor reference on wikipedia under scallion (which is the term I have to use now in order to find them in the market in the US :-) )

http://en.wikipedia.org/wiki/Scallion