One thing puzzles me and one thing I have a theory about.
The puzzle is this. The Ukrainian National Republic (UNR) managed to produce a five value set of stamps - the first General Issue - early in 1918. It was produced in large quantities over several printings and never used up - mint remainders even in complete sheets are common. It would have been relatively easy to add a few more values to the set.
So why did the UNR go to all the trouble of Trident overprinting its stocks of Imperial stamps? They could simply have been locked away and, for postal purposes, invalidated. True, it may have seemed good housekeeping (economical) to use them up. True, they provided a wider range of denominations with much - needed higher values. True, many of the stamps were perforated and thus easier to use than the imperforate first General Issue - but Tridents were also applied to imperforate Imperial stamps.
So this is my puzzle: the Trident overprinting, often highly labour intensive, could have been avoided by adding a bottom value (2 Sh) and a few higher values to the General Issue set and simply invalidating Imperial adhesives, thus avoiding the supposed problem of imports of Imperial stamps from Russia being sold as "Postage" at big discounts on face value.
Any answers to my puzzle?
And here is my theory (which is about another topic).
In many ways, you would expect the "old" Imperial high values - the 3r50 and 7r of 1904 on vertically laid paper - when overprinted with Tridents to have been bought up by philatelists and speculators since the remaining stocks of these stamps was small and probably known to be small.
But when you do see these stamps with Trident overprints they have often been used on Money Transfer Forms, with later punch holes and so on, and they often have early dates of use (1918 rather than 1919). Mint versions are often scarcer than used ones - for example, Kyiv I on the 3r50 grey and black is a very rare stamp mint.
So my theory has to be this: for some reason, perhaps becaue it was thought to be "methodical", these old stamps were overprinted early on and sent out to post offices early on where they got used up before philatelists had properly organised themselves. That's my theory.
This is not the whole story: there are philatelically-inspired overprints on the old 3r50 and 7r. For example, in the Corinphila catalogue you will see a very pretty sheet of the 3r50 overprinted with Kyiv III. This is almost certainly a philatelically-inspired production (and the inspirer: Svenson) and the overprint is a later type.
So there must still have been a few sheets of the 3r50 around even after Kyiv I and Kyiv II overprints had used (most?) of them up. Interestingly, however, Svenson could not lay his hands on a sheet of the old 7r black and yellow which does not exist with Kyiv III and this may be taken as a small bit of confirmation for my theory.