Originally Posted by
pinniped
Things may have changed in the couple years, but when I was last in London I could not get the Underground ticket machines to accept any of my credit cards. None have a chip + PIN.
At LHR, the HEX machine would accept only my Amex. None of my MC/Visas. Don't ask me why it was fine with my Amex...thank goodness it was.
So I took the HEX into London, hit an ATM using my normal card, and paid cash for an Oyster card in the tube station. It was very nice to have - the convenience is worth far more than any nominal cash savings you'll get out of it. Topping it up with cash was easy too - I never linked a credit card to it.
I had a friend here in November, and he had no problems using his non-chip Visa from the US in ticket machines. The AmEx vs. Visa/MC thing immediately suggests that you didn't call your card issuers in advance so they'd authorize your card abroad. This is not a problem with AmEx.