A curious rear mudguard

[Dr_Pinky]

I have a valanced rear mudguard, which I believe came from a late 30s military bike. However, it may be post-war. The valances are a different profile to those of M23/24, KM20 and early WM20 bikes, in that they become deeper toward the rear. These valances appear original, not later additions. I've posted under pre-war bikes and on the WD BSA site, but no-one's seen such a thing. Any clues appreciated!

Regards,

Craig