This is Australia's 1965 Christmas commemorative aerogramme. "19" of "1965" in the indicium was retouched as can clearly be seen in a detail scan.
This is Stein A-24C.
For the purpose of comparison a normal version is in the upper part of the image below, the reouched version in the lower part.
Reference:
Stein, The Aerogrammes of Australia and Its Dependencies 1944 to 1980
