Those damn Town Post offices...

I have already spoken a few times of the unpleasant discoveries that await the unwary postmark collector, and Town Post (sub-)offices are among them. They're not listed in any postal list that I know of, and I suppose it would take painstaking sifting through the Post-Telegraph Journal to find hard information on their opening and closing, let alone existence.
Here are a few Crimean examples, to set the scene:

This is Sevastopol' Town Post sub-office, one of two postmarks I know from that place and definitely the oddest. I found it in Bristol while visiting Ian Baillie.

A nice registered cover from Simferopol' Town Post sub-office, serial letter "a", but the same serial letter was also used for a smaller postmark:

Incidentally, under that British registration label is a Russian label identical to the label on the other cover. 

What brought all this on? Well, eBay spat out this:

A nice old postmark of Odessa's second Town Post sub-office. First time I've seen one, although Odessa specialists may have done better.

But you see the problem here...Town Post postmarks are like landmines for postmark collectors: you don't know where they are and how many there are. But they're very nice to find!