1E1:
1E2:
Then there is the 1E4 of 1940, with the watermark rotated by 90 degrees when compared to the 1E1 and the 1E2.
The last issue with this watermark is from 1951, the 1L1, with colors unique to this printing.
And then there is the clay issue of 1943. The watermark sons are ovals and the clay layer on the front of the stamp is shiny and reflective.