The card shown below has several interesting aspects. Right now Kiyoshi Kashiwagi is consulting philatelists in Japan, trying to help me find the answer to one of them: how did it get from Shanghai to GB starting in November 1942.
That it did make it is established by the UK censor handstamp. I think that it was not Red Cross mail, as there is no docketing to that effect and as there are no German censors, which I would expect had it been sent through Geneva.
I'd appreciate your theories, or better yet, your documentation, for its likely route.
Thanks,
Dann