Dear Ron,
Great posting! Thanks for opening the subject!
I'm happy to say that I found two big control blocks in my mess… one 5x5 and the other 6x6, one the early 1936 printing and the other from the late with bar printing.
The stamps at R17/4 both have a flaw beneath the ear lobe, but they are slightly different from each other, and both are slightly different from yours. There's some kind of progression - or regression (?).
The implication that I read into this is that it is a weak flaw on the cylinder that was subject to slight modification (reduction?) by the act of cleaning and re-chroming. The inference then is that there were two rechromes? So three states for the cylinder at least.
To sort this out it would be very helpful indeed to see more material, and I guess we both hope that there will be further contribution to this subject…
CALLING ALL COLLECTORS WITH KEVIII MATERIAL!!! : )
Cheers and all,
Robin (R)