Oh sorry, didn't know you were talking about an opt-in list. After re-reading your post and your last one there it is glaringly aparent.

You see, there is a big database that holds everyone's bankruptcy ruling and details if you were ever bankrupt in the UK. It is used mainly by credit companies and banks to help judge if they will be repaid their loans, but can be accessed by most people. I thought that was the one being used. An opt-in list should be 100% okay.