you have any links to descriptions of this?
I learned of it during a conversation with an extremely well read Scot who grew up in England. We were discussing World War II (I am writing a book) and he gave me a several leads which proved beneficial. I have no reason to question his word. As it was outside the scope of my book I never pursued his comment with research. Since he now lives in Australia, I would assume he knows what he is talking about.