Hi Denise
A possible death for William Mitchell in 1956. His mum is at Rookwood Catholic and through the Catholic Cemeteries search I found this that would match with his age at death having been born in 1892
http://search.catholiccemeteries.org.au/default.aspxA search on NSWBDM found a William Mitchell death 1956 with parents Thomas and Catherine.
Just because we don't know the identity of William's birth father doesn't mean this couldn't be him. Whoever gave out the info upon his death may have known a fathers name. Have searched all possible deaths for either Mitchell and Gordon and haven't found one, up until 1985 anyway, that lists a mother with name Catherine.
A possibility worth checking out?
Karin