I called Walls to check if Magnum, Cornetto or Vienetta were suitable for Vegetarians or not. The CSR told me that all Walls ice-creams (except Ben & Jerry's) are not suitable for vegetarians as they use whey powder from a cheese supplier or from calf rennet.
Interestingly, the list suggests that Mini Magnums are veg. I did not ask them about eels but the Careline is on 0800 010109 if someone wants to check.
Hope this info helps clarify the issue.http://www.scribd.com/doc/145564872/Unilever-UK-Ice-Cream-Vegetarian-List