This search took me in to the archives of the Sydney Morning Herald and the National Library of Australia's digitised records. I found the service record of 60218 Pte William George Field easy enough and this gave me his wife's name but the path ran very cold with his death in 1958. A search of the newspaper records showed that he was divorced in 1920 so I had to look and see if he remarried and if he had any children.
I found William's funeral notice which gave me his second wife's name, his daughter's married name and his grand daughter's first name. The unusual combination of names made locating the grand daughter reasonable easy, thanks to the Internet.
The British War Medal awarded to William will be returned to Toula in the near future and thanks to Adrian for taking the first step to see this medal sent home.
The returned medal tally is now 985.