The Barclays Aviator MasterCards have no foreign-transaction fee. That's a good thing, unless you want to make purchases from foreign merchants while you are not in the merchant's country.

That is, if I've notified Barclays that I'll be in another country and then try to use the card there, it works.

But if I'm only planning the trip and want to buy train tickets or concert tickets in advance, or order a map from Amazon in Germany, the charge is invariably declined. This also happens when I try to top up my Skype account (billed from Luxembourg, it appears), or pay for business services or downloadable software.

I am not ready to start telling Barclays that I will be in Germany for the next three minutes while I purchase from amazon.de or bahn.de.