Japanese Occupied China to GB

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
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