Have you tried talking to US banks that have UK branch offices? Note that even those who don't have consumer branches may still offer accounts at those branches. E.g. Bank of America has a huge presence in Europe, mainly via MBNA and Merrill Lynch, but also some other services - I don't know if they offer accounts (the way to find out is likely to talk to their US international banking team).
I know that may be non-ideal for you from a risk POV, but you may also find the UK amusingly (or infuriatingly..) bureaucratic and byzantine in that having a UK bank account is the best way to prove to another UK bank that you are worthy of opening a bank account with them afterwards.
I know that may be non-ideal for you from a risk POV, but you may also find the UK amusingly (or infuriatingly..) bureaucratic and byzantine in that having a UK bank account is the best way to prove to another UK bank that you are worthy of opening a bank account with them afterwards.