I haven't come across this here, so I figured I'd post it.
If you have an American AMEX, you can transfer it to the UK, and they will approve it based on your American AMEX history.
We applied for a transfer, and were told today it has been successful!!!
Finally!!! I've only had a basic bank account with a cash card until now, but I presume once the AMEX shows on my credit report, my ratings will go up (well, have to use it too I suppose..)!!!
We've been surviving with two Finnish credit cards until now, but the funds we left behind are starting to run low, so it was definitely high time!