I am not tying to raise "all sorts of possibilities" I am simply trying to help you with your search.

The identifying of the cap badge is the fastest and simplest way forward with your chap. I have narrowed down the most likely candidates and with a little footwork from your goodself in...
a) Looking at the MICs to find named matches and then
b) Matching those names with the Regts / Corps mentioned or
c) Putting up the names if no matches...
...will help you in finding what you require. We have on RC managed to find the right chap with just as little int previously!

Again, a better scan of 300-600dpi would help...There may even be shoulder titles or something else on there...

The Regt/Corps is the key, and with that you can then look at the surviving records and perhaps the pension records. This is why we are trying very hard in ID'ing the Regt for you, so you can go thence to the MICs. Then they are not a "waste of time" as you put it.

As for Australian Forces being "far superior" this is a matter of personal conjecture and not "fact".

All Empire, Dominion and Commonwealth forces fought with equal courage and determination. Indeed they were all trained the same, and I feel that although your Australian Pride is commendable, the statement is somewhat disingenuous.

As I have mentioned in my earlier post, many Australians DID travel to the Mother Country to enlist...Perhaps this Australian yr 12 school lesson will help you sort "fact" from personal conjecture? ..."96% of Australians in the 1911 census were of British stock". There was not the republican zeal in 1914 as is found today, apart from the Fenians!
https://internal.shenton.wa.edu.au/society/12History/WW1(1).pdfIt is indeed fortunate that the Australian Military Records are so complete...The British ones are not. This is a fact, and one we cannot change. It would of course be much more simple had our ancestors labeled EVERY pic with name rank and number...and place and date, but of course much of this would not have passed the censor. If one is fortunate enough to have the medals in the family, then this is of course a great help, as all int is available on the rims/reverse!