I think I read it on here so had a quick google..
//Fascinatingly, Walker's cheese and onion crisps are suitable for vegetarians, while their mature cheddar crisps are not. One might assume that all the space for onions is filled up with rennety non-vegetarian cheese powder, but in fact the presence of vegetarian cheese powder in the cheese and onion variety was something of a victory for the Vegetarian Society, which awarded the crisp with its Imperfect World prize in 2003, prompting Walker's to change its recipe. "People assume," says Chris Olivant of the Vegetarian Society, "that because most cheese on the shelves of British supermarkets is now vegetarian [90%, in fact], cheese flavouring in crisps will be too. But it's not".//
From...
http://www.guardian.c...ay/15/foodanddrink.uk