1912 Sveriges Forsta Flygpost

I am looking for articles as to why this stamp is considered a semi-official airmail stamp.

Thank you.

Hi.
https://svammelsurium.blogg.se/2014/september/

Thank you
I've been able to find information about the stamps usage in 1912 but not much information about it's 1937 overprint and usage.



The 25th anniversary stamp.

A nice run down on this obscure stamp.
http://www.stampnotes.com/Today_in_.../092712.html

My 1946 Sanabria calls this the Stockholm Demonstration Flight issue. Covers were flown on a demonstration flight around Stockholm and received a double-circle cancel in violet with a September 1, 1912 date.

There is no explanation for the anniversary overprint, other than "issued September, 1937."

They're perfed 12.5 and the 1912 issue is also found imperf for a 2x premium (in 1946).

The Facit Special Classic 2016 catalog provides a paragraph:

"First Swedish Air Mail, Silver jubilee 1937"

"No. HF1 overprinted in black. The stamps were sold at 3 kr each but had no postal value. They were used on Sept 16th for 4800 letters and cards together with current postage stamps, and sent by a Jubilee Flight. For the cancellation the official hand stamp illustrated here was used. Unused copies were not sold, but a certain number were given away free."

Robert