Hi All,
So, I got an Oyster card on my latest trip to London, and loved it.
It's so convenient. I did register it.

I'll be back, passing through, in early August, and would like to add
some Pre Pay value in advance for use then. But, apparently, I have
no idea what the answer to the "Security Question" on the registration
form is. Is there any way to get an online account without that
information? And even when I get in, will they accept US-based credit
card details?

73, doug