I have been a happy drinker of stones alcoholic ginger beer for some time and based on internet websites with information on alcoholic beverages here in australia it seems it was vegan. The other week some friends and i were enjoying a few and went back to buy some more. The new lot tasted far different and looking at the label in comparison to the previous drink we'd just had it was apparent they'd changed the recipe and added glycerol. I've emailed them asking for a response about this product and haven't had a reply yet. I think for the best part it's best to leave it out. Shame really. It's no great loss at the end of the day as the new recipe tastes disgusting.
Now it's worth noting i'm talking about the australian stones alcoholic ginger beer made by angoves under license from the british company. I don't know what the story is with other countries but it may be worth checking, just in case.