Well, the person in Rahnee's photo appears to be a General Officer (Staff Tabs and General Staff hat badge) with Medals : 1914/15 Star, British War Medal, and Victory Medal with MID Oak Leaf, Volunteer Decoration, and a slightly obscured medal that looks as if it could be the Croix de Guerre. Around his neck is the insignia of a KCB and centrally beside the row of medals is a seven pointed "star", the insignia of the KCMG.
All of this fits with it being Sir John Monash, unless there is another WWI General of similar appearance and awards.
Perhaps family memories were confused ??
Maec
Based on this information and that fact that his birth isn't checking out either, I'm really starting to doubt the information we have on him. Several family members have this photo along with the photo of his wife, and all believe it to be him. But in all honesty, if he was such a decorated General, there would be some record of him, and there is not.
It is definitely not a picture of Sir John Monash. I've also found images of four of those listed above, and can confirm that they are not the same as the photo we have.