OS PUNCTURES and OVERPRINTS
Until recently (1970s) perforated OS issues were seen as inferior space fillers, or collected at the back of the book. Although they rated a mention, they were not viewed as collectible in their own right (much like postage dues).
From the very first days of the Australian Colonial issues, various state departments used some method to identify their official status. WA for instance used commissariat punctures (2 types) on the earliest WA swans.
The purpose of all official stamps was clear, they were issued free of charge to the relevant departments, specifically for departmental use. Ie not public, or personal, use. As such, OS stamps were never available, nor sold to, the general public. To do so would destroy their intention.
The one exception to this occurred in the 1930s Kingsford Smith, and caused the immediate abandonment of OS markings altogether.
Not being on sale, mint copies are supposedly scarce. However, heavy trafficking occurred in these issues at all times, and were thus collected mint. As a general rule, they are about equal in scarcity, used or mint.
As to their inferior space filler quality. It is true, and for the wrong reasons. OS stamps normally originated from rejected normal printings. Either poor print quality, bad perforations, poor paper, or a combination of them. Sometimes an entire print run was devoted to the OS issue (to use up poor quality paper), or similar eg the NWPI 2/- Roo issue.
For the Kangaroos, three types of OS exist.
Perforated Large OS
Perforated Small OS
The large OS came first. It was devastatingly bad. The stamps disintegrating as a result. The small OS subsequently became the mainstay of the Kangaroo officials. Overprinted OS appeared in later printings of the 6d only. (The 6d wmk CA anything, is scarce as it was quickly superseded by the 6d Kookaburra).
The OS table below neatly illustrates:
Unlike all other issues of the kangaroo, there is no recorded instance of a 2.5d OS variety except by Robson Lowe, and, one example sold by Robin Linke in 2008. As punctures are easily forged, it remains conjecture whether this denomination exists perforated or not.
No OS punctured stamps were produced (via the Archival records) between June 1914 and May 1917. Below is the table of when each denomination on KGV paper was released. Only the 5/- and the 2d fall into the region of punctures.
For most denominations, therefore, it is unexplained why any OS punctures appear at all, on this watermark,
(The 1d is also a problem, as it is unexplained why small OS and large OS appeared together across several plates and printings. Large was supposed to be abandoned).