Re: @ Toilet Duk
My concern is that if ID cards are required to access certain services, and are biometric (read, expensive) I would only want to carry it when I needed it, for fear of losing it, and becoming a non-person until it was replaced (which I presume would cost me some money, ~the cost of a new passport (£75 or £85).
A Driver's License is just £14 if I need to renew online,... hence I'm happy to keep that in my wallet.