John is definately son of Bernard, grandson of William. But he was in his twenties no earlier than 1943 (it may well have been later - I had used this as a "look no earlier"). What is now clear is the author was unaware of William's death in 1936.
Thanks once again for all the pointers - there are clearly many Australian resources now online that I wasn't aware of. I've located Trove, but where did the WW2 records come from?