Thanks, Paul, if his wife's name is Isabel, I probably have the right person as John R. Jacka married Isabella Nelson Finlay, and the "R" in his name stands for Richards his mother's birth surname. I think his profile is a duplicate of Jacka-1134, so I will merge the profiles. Isabella died in 1927 so it will be another 26 years before her profile is due to be open - so I will put notes for her in the research notes of John's profile.
Thanks for your help