Hi Michaela,
Don't often find this sort of thing - a photo of Robert Strathern actually as a prisoner of war in Dulman POW camp (he's the one sitting in the centre of the photo). Taken about September 1917.
Found it here:
https://www.awm.gov.au/collection/P03236.253. All public domain stuff. (Hope it is attached!)
Comes with the following annotation (cut down version):
Outdoor portrait of four allied Prisoners of War (POW) at a POW camp at Dulmen, Germany. Soldiers are gathered around a table covered with a tablecloth on which is placed a vase of flowers and four glasses of beer. The three soldiers on the right are holding cigars. Identified from left to right: 2729 Private (Pte) Oscar Keenan, 53rd Battalion, from Bengara, NSW (standing); Pte R. Strathern, 2nd Otago Battalion, New Zealand (sitting); 4512 Pte Percy Arthur Haslam, 54th Battalion, from Newcastle, NSW (standing); and 4151 Pte John Joseph Costello, 54th Battalion, from Sydney, NSW (sitting). One of a series of over 400 photographs sent by Australian POWs in German camps to Miss M. E. Chomley, Secretary, Prisoners Department, Australian-British Red Cross Society, London. Original album housed in AWM Research Centre at RC00864, Album image number 304.
Cheers,
Bunny