Australia
Invalid Stamps Used on Aerogramme Form

This is a privately manufactured aerogramme form licensed by the Australian Postmaster-General (permit no. 8, manufactured by McCarron, Bird & Co, Melbourne). It was sent from Melbourne (cds SHIP MAIL ROOM MELBOURNE 29 MY 62) to the sender's postal chess partner in Luedenscheid, Germany.

The aerogramme is franked with stamps of Nauru with a total face value of 10 pence. The stamps of Nauru were never valid in Australia.

In his message the sender states:

"This time I am answering with some stamps of Nauru [...] However, I would like to point to the fact that I cannot ask for a clear and light cancellation of these stamps at the post office. The more I insist on this the higher is the risk that the stamps will not be accepted, which would result in the aerogramme to be sent by surface mail.

It is in particular complicated with the stamps of Nauru. I could send the letters to Nauru first to feed them into the postal network there. As Nauru does not have an airport, this will result in about the same transit time as for a seamail letter from Melbourne."

Apparently, the sender wanted to offer his chess partner with the correspondence not only stamps of Australia but also from Pacific Islands. He hoped that the stamps of Nauru, which were not valid in Australia went unnoticed through the Australian postal service. 

It is interesting that he mentions the risk of the Nauru stamps being detected but the consequence he saw is a little bit odd: it is not only that the letter would have been diverted to surface route but that it would have been taxed as short paid. I guess his chess partners would have loved to pay for each move they receive.


References

Thank you, Allan and stampboard members Tassie_Stamps and GlenStephens, for the information that Nauru stamps were never valid in Australia. Here is the link to the stampboards thread concerning this matter.

A list of the manufacturers of the Australian permit aerogrammes is included in the article "Australian Private License Airletter/Aerogrammes 1946 to 1969" by David Collyer in the May 2012 issue of the Postal Stationery Collector.