And Now For Something Slightly Different.
Unusual to have the two varieties in one block.
Cylinder block of 4 1A 1A 1A 1A 1A
From initial stock supplied to Brisbane Philatelic Office with marked flaws behind the left and right shoulders of the Duke. This is the only 1A(black) cylinder I have seen. I am surmising that the flaws were noted and corrected pretty quickly as I have a block on which the 1A black cylinder was replaced with 2A. There is no trace of any flaw on that block nor on the other cylinders I have seen —
1B 1B 1B 1B 1B and 1D 1D 1D 1D 1D
If anyone has a block similar to the image here I would be pleased to hear from them with their comments.