I can’t find much precise, reliable information on the photo, but it is presented in the book The Digger’s View by Juan Mahony. If anybody wants to track down a copy there might be more information inside.

Interesting, I tried to find some info on German POWS in Australian hands during ww1 but all I could find were studies on he German-Australian internment camps. They were treated as “foreign aliens,” much like the US did to Japanese-Americans in ww2. The Australian treatment of Germans sounds much more humane, however. They were interred, yes, for their heritage, yes, but apparently they were allowed to basically build a society with theater and arts etc. Although they were forced to correspond with outsiders in English and the letters were heavily censored and any foreign language writing was confiscated immediately. Interesting bit of history. This photo seems…oddly lighthearted for the given situation.