Ugly bug ball

Fellow Gardeners,

Does anyone know what this creature is please?  The Austrian lady on our plot keeps asking me questions, thinking I am a gardening expert or something (I think it's because I am a lot older than her and I have a kind of wise expression). I hasten to add that I am a keen gardener but far from expert. Anyway, she showed me what she had dug up on her shovel and I blithely said, oh I have seen that here before. I don't know what it is but I don't think it's anything dangerous.

What a big fibber I am. In fact I have no idea.  If anyone recognises this villain please let me know. It's about half the size of a thumb.

Anton

And in gardening terms, it is a baddie.  Eats roots, and then eats some more roots ....  Often found under grass (which is why those who love their lawns dont love it) and in grain fields.  No chemical cure either,  all you can do is slaughter the larvae to reduce the life cycle.   

Thanks for your replies.

Anton