Hi Wayne, I haven't really done much research,but I sit back and marvel at some of the other people who are so kind and generous with their own efforts.I suspect Gordon BEACH has had that effect on most people,with all of his extra ordinary research,to aid so many other researchers.He is a real gem and he has helped many,many people on these messageboards.
Getting back to your query there was a Ruby HARDING who married in Brisbane to a Douglas William GIBSON on 31/3/1917 (Queensland Marriage Reg - 17/B019977).
On the 1922 Electoral Roll it lists the above male Douglas William GIBSON as at the "Place of Living" at Kedron Post Office in the subdivision of Nundah in the division of Lilley.There is also a Ruby Gibson listed at Kedron,but you would have to look at later Electoral Rolls to see that they were in fact a couple(It is possible to search Queensland deaths up to 1964,just to verify that this Ruby was Ernest and Maria's daughter.
Mary Ann HARDING(Ernest's mother) looks as though she re married to a John Poole McLEISH as there is a death of a Mary Ann McLEISH's death with parents Emanuel WATTS and Anne SANDERSON on 5/1/1903 Reg - 1903/001348.
The reason I tried looking at another marriage is that Ernest was the last child of John HARDING and Mary Ann WATTS and there were two John HARDING deaths recorded in Queensland Country in 1867.The marriage of John Poole McLEISH and Mary Anne HARDING was on 4/11/1867 in Queensland Country(1867/000160).
John Poole McLEISH was listed on the Electoral Roll for 1880 to 1884 at Drayton & Toowoomba,so I would suspect that Ernest and Maria were possibly married in that area.
Florence,Arthur John and Ernest James Harding (Junior) are all buried at Toowoomba and Drayton Cemetery as well there is John HARDING who died in 1867 (Ernest James HARDING (Senior's) father?).
John Poole McLEISH,Mary Ann McLEISH and possibly Ernest James' step brothers and sisters all look to be buried at Toowoomba and Drayton also.
It may be worthwhile to ask a kind soul to see if there is an obituary for Ernest's mother in the Toowoomba newspapers.