We used our Bank of America ATM cards with no issues at various
Barclays ATM each time for £250 with a cost showing on our US account
of $467 and $477, due to changes in exchange rate I guess.

Harrods charged one purchase in US $ on a visa card, and I "think" one
other transaction for some reason included a $1.70 foreign access
charge, but I don't recall what it was related to.

So far nothing too exciting is showing up, other than the horrible
total of course.