Bill - unfortunately, in all of my investigative work, which has taken me all over the US either in person or via phone coversations, I have yet to turn up any birds that do not trace back to Glenn's flock after the addition of the outside blood. The flock that you are referencing from Decorah around 20 years ago, is to my best guess, the flock of Ransome Bolson, and it was around 30 years now. But Ransome's flock has been gone for quite a while now and none of his children know what happened to the flock.
We do have an option on our website (put together by the talented Connie Hurley) to send an email to the club in the event someone locates or is raising any birds that did not have outside blood. So far this hasn't turned up any leads, but maybe someday........
It does seem very unlikely that a strain still exists without the outside blood.
What is neat about this breed, is that all the components of the original stock is still with us and are still being expressed. We as a club are in the works of figuring out what should and shouldn't be here.......every month seems to bring us new information which brings us closer to restoring the type and color of the original lines.