Hi Rowan,
Thank you for your e-mail.
I'm surprised that it can ever be as complicated as needing that - the way I understood it, the cookie can only possibly be stored for 'en.wikipedia.org', '.wikipedia.org', or 'wikipedia.org'. That's not really many options to try, and, as I say, as far as I can make out it's the very first one.
Perhaps these domains can be listed on the page with the cookie error please. At least as suggestions for starting point to try and resolve the situation...
Don't get me wrong, I agree that *something* failed to give you the information you needed, but in this case I think it was Mozilla's cookie system doing too much automatically, and not giving you a decent UI to undo it.
I think Mozilla did now me it, but I did not click "Details" to see the hostname. I get cookie requests all the time, I wish to avoid being someones advertisement profile, so I deny all for which I do not think I need. Very few sites have errors this way. Although in this instance Wikipedia website did complain. So then I had the problem of trying to find which host the cookie came from, www.wikipedia.org no.. etc etc..
I have removed the block now, and the wikipedia.org site works ok with the cookie.
Thank you for your help.
Kind regards
JG