What are you hiding?

Jack Straw's comments on Muslim women who cover their faces by wearing what I now understand are called the Niqab and the Burqa have predictably polarised public opinion. I have to say that I always feel slightly uncomfortable when I come across such women - particularly those wearing the Burqa, where the face is completely covered, with just a mesh over the eyes for them to see through. But why? Straw bringing the issue out into the open has made me think about this, and I've come to the conclusion that, for me, it's not anything to do with it being a statement of difference or anything like that - it's simply that I associate people covering their faces with a wish to conceal their identity - usually for nefarious purposes. It's what kidnappers, bank robbers and terrorists do, so that's the basis for my feelings of unease - completely irrational I know.