What a good idea Mr Red. Good thinking! I wonder if there's a simple protective wallet one can buy which does the same job as your mu-metal sleeve on your credit card? My husband travels with two passports (dual nationality) and his bank cards, and has to board three planes to get to his destination in Africa. It would be good to know he could protect both passports in some way from unofficial scanning!
I really did NOT want a bank debit card which does that non-contact paying rubbish. But you have to get a 'normal' one specially from the bank and you have to pay. I must get round to buying a protective little wallet for my cards. Sigh...