Re: Champagne Cider
There's a specific exception for Champagne Cognac in the original registration mark for Champagne, because it was already in existence, and derives its name from the region in which it is produced; although that is not the same region as the sparkling wine.
Usage suggests that is does indeed only apply to sparkling wine however as, contrary to the original poster's assertion, Bulmers won the case brought against them by Bollinger, as they were using the méthode champenoise to produce Pomagne. However the year after they won the case they switched to bulk industrial fermentation, and therefore could no longer justify the "champagne" tag.
Cheers! :)