Greybird - I think you've got the right connection - I learned that green was the Druid's colour, and that until it went on-line that was why anonymous letter-writers used green ink. Also, I know a few people who are fine with green, but wouldn't wear it to a wedding.
An Irish friend who had a more pagan than catholic background told me that green was the colour of ancient Irish royalty, but I haven't a clue if she knew what she was talking about!
Nothing else to add, but thanks for the links!