Description:

1921 (Sept 30) Adelaide-Alice Springs #55 cover to Unley, SA carried by Francis Birtles and pilot Lt FS Briggs in a DH4 on their Railway Commission survey flight, franked with KGV 2d orange tied Adelaide '27OCT21' roller cancel on arrival also tying Northern Territory 'Stamp Duty' 1d violet with manuscript date '20/10/21' affixed alongside on face, plus 1939 letter from Birtles authenticating cover as 'most likely sent from Alice Springs or Charlotte Waters', Cat $3,500. [one of only three items known; the Eustis example without NT Duty stamp sold for $4,078]