If you are currently in London, check out Citibank. It's my understanding that Citibank in London will open a USD account for you (are you a US citizen? - that may be a prerequisite). You could talk to them and see if that would be sufficient for transferring payments to your US credit card.

We have obligations in the US and so just kept our accounts active when we left the US last year. The bank just changed our address and we have no issues. We bank with a smaller bank though with good service - they actually know who we are which is always a refreshing change from just being an "account number" at the larger US banks.