As I wrote in my last post, there is some more information on this airmail set to come. Here it is.
On the deposition of Sultan Ahmed in 1925, stamps with the name of the new ruler Riza Shah Pahlevi were pressed into service and overprinted with his name.
They were followed in 1926 by the first stamps of Riza Shah, the title Riza Shah assumed as a result of his succesful revolt.
In 1930 a handsome air mail set appeared, completing the current definitive issue and using the same portrait of the Shah. The design, as I have said, showed an eagle flying the Elburz Mointans, was in horizontal format printed on white wove paper in photogravure up to the 1 Kran value and above that value recess-printes. All values were line per 12 1/2 X 11 1/2 and printed by J. Enschede and Sons.
All values are known with digital "Specimen" overprint on the lower right of the stamp.
These two fine sets were followed in 1931 by a shorter set to 1 Kran and 27 chahis, litographed in two colors by the Mejlis Press. As in their previous productions there was a great range of shades, and though they improved on earlier productions, they were still far behind the quality of the Dutch firm.
As other stamps, the whole airmail set was overprinted in 1935 with "Iran", although its values were also expresse in chahis, Krans and Tomans. The last stamps to be issued inscribed in French "Postes Persanes" were a series of nine pictorial stamps commemorating the tenth anniversary of the Shah's accession. All future issues were incribed "Postes Iraniennes" or simply "Iran".
There are minor varieties on the overprint on this airmail set, perhaps the most noticeable being a short last serif on the "n" of "Iran" and a lengthened serif to the "a" joining it to the "n". Forgeries were not seen by Brigadier H.L. Lewis, who wrote a remarkable book entitled "The Stamps of Persia".
My information as laid out above comes from this book. I think it is a rare book in itself, as it dates from the early seventies of the last century and published privately. It lacks illustrations, but the information is there. I believe reprints of this book exist. The Introduction is headed "Adventure and Discovery in a Philatelic Jungle", any collector of Persian stamps will agree this is a suitable heading to start a book on the subject!