Help! Russian Offices In Turkey

I found these among a batch of world local posts. They appear to be issues from Tsarist Russia - offices in Turkey from the currency used but I may be wrong there. I cannot find any reference to the overprint at the top of each stamp nor some of the currency overprints.

Are they official issues or are the overprints applied privately. If so, what agency is doing these overprints and for what purpose?

I have grouped the stamps, mostly according to the overprint and the base design and have shown each of my groups with a close-up of one denomination to show details of the overprint.

The letters at the top spell out "ROPiT" in the Russian alphabet and these were the initals of the Russian Steam Navigation and Trading Company of Odessa which was one of the biggest steamship companies in Imperial Russia.

It was established in 1856 and ceased to exist in 1918 due to nationalization after the revolution in Russia.

In 1901 it had a fleet of 72 steamships[3] and the company was listed on the St Petersburg Stock Exchange (info from Wikipedia).

Some of the early stamps listed in catalogues under "Russian Post Offices in the Turkish Empire" (or "Russian Levant") were issued by ROPIT and their offices acted as post offices for the Russian administration in the Turkish Empire.

The Russian post offices in the Turkish Empire closed in 1914 and the ROPIT offices were left with stocks of these Russian stamps with the diagonal surcharge in Turkish currency.

In 1918 at the end of WW1 some of the ROPIT agencies reopened briefly and the old stocks were overprinted like these ones with the company initials and with new surcharged values reflecting the depreciation of the Turkish piastre. However, these stamps were never used postally. SG used to list them but haven't done so for many years.

Thanks for the information. The ins and outs of history never cease to fascinate.

Great information Nigel,
will be going into my album.

.....and it came in handy tonight

Are these listed in any catalogue.
I tried a 1981 Stanley Gibbons but they're not listed.
How many different stamps were overprinted?