Well, I don't even think there is a glimmer of hope, the rules are "cash account", a "cash like account" is not a cash account. I guess strictly speaking, they could refuse to accept an American Credit Union on the basis that you own shares and not cash, but maybe we don't want to put any ideas in their head.
Not to be confrontational, but arguing with us isn't going to make us change our opinion, which is what it is at the end of the day. You are free to do whatever you wish, but trust me that UKBA is going to spend even less time considering the finer points of your policy then we have here.