Hello,
Just a note: caveat emptor.
In my opinion, the 'Walter Blume' signature is a forgery. This Belgian postcard seems to be labeled at the bottom as showing "Thieffry". That would probably be the Belgian ace Edmond Thieffry; the pilot in the front clearly resembles Thieffry. He does NOT resemble German ace
Walter Blume. In my opinion, this postcard has nothing to do with Walter Blume.
In my opinion this is a post-war photo of a captured or interned Roland-built Halberstadt CL.II, which had been taken over by the Belgians. The cockpit has been modified by the removal of the gun ring. The painting over of the fuselage cross may have been a start on converting it or at least covering it up.
That's just my opinion- and that's all it is. I'm not accusing the seller of anything; he may have been taken in by someone else.
Take it or leave it.
Greg