Well, I don't know about the Bannerman conversions specifically, but I heard about one conversion (or set of conversions) done by a radical of some sort. I really can't remember if he was a fascist or a communist, but he bought and converted a bunch of M-Ns that didn't get delivered because of the October Revolution. He was trying to build up a private army that would be able to overthrow the government. Needless to say he failed miserably, but I really can't remember his name or any other real details. I read about it in an older Shooters Bible or something like that I found at the library. Anyway, if it happens to be one of those, I'd say it's worth quite a bit of money. If not, it's just a weird/dangerous conversion. Anyway, hope someone who has more concrete details comes along. Good luck.