Cool smock! Looks like one of the very first, rough patterns (ca.1938). The names of the patterns itself are post war terminology, so if we try to name it, well, it may be something like "Platanenmuster prototype"
or similar. Something like that you can find in Beaver's books, however the "norwegian" one has extremely large spots. Early smocks can be seen quite often on the pics from french campaign in 1940.
Btw. what's the pattern of the Zeltbahn your friend has got?
