cannibalism with the celts

[Quintus Aurelius Lepidus]

Hi

I've read several archaeological hints about cannibalism during the british iron age.

after some googling I've found this article and some others as well:

http://www.bristol.ac.uk/news/2001/cannibal.html

Now, what I do wonder is, how widespread was this?

and second of all, is there proof that the mainland celts from gaul, spain or the germans did this as well?