if you want a dollar credit card (because you have dollars and want to spend them in pounds), the one many people use is Capitol One Visa. You need to use an american address for it (brother, etc). They don't have a foreign transaction fee. Short of the interbank rate - which mere mortals can't get - Visa and Mastercard are about the cheapest exchange rates around. After lots of currency maneuvering, I find this the best and easiest way to change dollars to pounds. Very happy to hear of better arrangments.
What I'm looking for is a dollar bank account with a debit card (Visa or Mastercard) that doesn't charge the foreign transaction fee when you take out pounds at a UK ATM. My Credit union adds 1%. (You can do it with your capital one credit card, but you incur interest.)
I'm a little concerned that this subject might not be correct for this tax forum but maybe belongs on a different one. ?