I found this doing a google search:
http://www.dailymail.co.uk/pages/liv...n_page_id=1774 Veggies vow to boycott Mars bars
By ELEANOR MAYNE
Vegetarians plan to boycott Mars bars after their recipe changed to include animal products.
Other big brands from the same company -including
Snickers, Galaxy, Twix, Bounty, Milky Way, Maltesers and Minstrels - are also affected.
From this month, chocolate manufacturer Masterfoods has started using rennet - an enzyme taken from the stomachs of newborn calves - to make whey for its products.
It had previously been relying on a readily available - but more expensive - vegetarian alternative to rennet.
The firm makes three million Mars bars a day in its factory in Slough.
Vegetarian Society spokesman Liz O'Neill said: "People will not like the idea that you cannot make a Mars bar without killing a calf.
"We have had no good, clear answer from Masterfoods why they have to use animal products when all these items were previously produced using vegetarian alternatives.
"But we can no longer describe any of them as suitable for vegetarians."
Any bar with a 'best before' date after October 1 this year is now no longer classed as vegetarian. The firm is offering a refund to anyone who has bought a bar but does not wish to eat it.