From a plate perspective, watermark, paper and even colours, are not interesting.
The 1d KGV Surface Printed stamp appears to have a bewildering array of varieties, shades, perfs, colours, watermarks, plates, dies and papers. The apparent complexity is simply because it was printed in BILLIONS. As a result, the 1d KGV (red particularly) is the most studied stamp of the Australian Commonwealth, because of it's abundance, cheapness, and ready availability in BULK. A lifetime's pursuit can be spent inside a single cardboard carton.
This has naturally led to a wealth of recorded detail. Giving this issue a perceived importance it doesn't deserve. A lot of text is generally devoted to two factors.
The stamp is so common and in such profusion of varieties, that many of them were not noticed until decades later. However, with the never ending research that this denomination engenders, much of the progressive plate varieties are known, and, similarly, plate positions. It gives the impression of a seriously complex issue.
The only properly complicating factor in the 1d, is the use of different papers of distinctly different character all issued (more or less) contemporaneously. The KGV watermark is the keystone to the series, but, even with in it, seriously different stamps occur thru the use of rough and smooth papers from wartime conditions. Similarly, emergency issues on No watermark and Multi watermark (all issued during same period) add to the difficulty of classifying what's which. The key, is in the plates and their imprints, not, the papers in general use.
The 1d can be summarised and collected as follows;
To this list can be added line perforations (on smooth paper), and monograms/imprints. Naturally, it should be recognised that not all monograms/imprints and flaws appear on all of above, simply because the offending plate was not in use.
Finally, the Perkins Bacon set of 4 steel plates were in use continuously for 23 years until the end of the issue. Interweaved throughout the story, is the removal and re-emergence of the left plates. Their presence, or lack of, becomes critical in understanding rusted cliche and die2 varieties, to say nothing of imprints and monograms.
rusted cliche die 1 and 2