Wow! Thanks everyone for the information so far, and more than that, thanks for showing me the use of far more diverse resources than I had contemplated using so far. An object lesson on how to proceed in this hobby for me, both in sharing of resources and techniques. Sorry I am not quite in NZ's timezone, so the day is just starting for me here in Japan, hence my tardiness of replying!
Yes I am directly related to Frank Poore - he is my great grandfather. His disappearance was a real shame, because it cut me off from one side of my family. I grew up with the Moodys, often staying with Mary Elizabeth, and knowing her younger siblings. Unluckily I was too young at the time to care about asking her the crucial questions that might help solve this mystery!
The extra bits I know about Frank Poore are that he was a stage entertainer, performing as a magician. Mary Elizabeth Moody would tell us tales of being cut up in half, and riding unicycles on stage, something I could never quite square up with the image of the loved but rather acid tongued person I knew. The Poore family is a musical one - Franks grandfather was a professor of music in Bath, his father was an amateur flautist, one of his brothers George Edward was a professional musician, and George Edwards son Francis Edward Graham Poore was given a MBE for his services to music. So this fits in with the family's arts orientation, making it easy to imagine that the censorship story (which I have never heard about before) might involve him as well.
After Frank left, Mary Elizabeth was remarried to William Little in 1920, and later to Walter Fraser circa 1944 (he is also rather difficult to research). There were two children with Frank, who have been correctly identified here, Elsie May Poore and Henry Francis 'Harry' Poore. They were never formally adopted by William Little, but you can find them in the records using his surname.
Mary Poore's will really does suggest that maybe Francis William was dead (or maybe disowned by the family) by 1938. Certainly all the others are accounted for in the will, and the known others are dead by that stage. I can find no death notices for him at all anywhere. The Australian one indeed doesn't check out in the end, and I can't find anything in English records as well. The name luckily seems to be fairly rare - when you search you don't find any Frederick William or Frank Poores anywhere!
I will post this, and try to look up more details about ships and education records, as well as addresses. I see the the Hereford St address is actually mother and father Poores address in the 1914 and 1935 electoral rolls. A mystifying thing is that Mary Elizabeth Poore never seems to appear in these rolls, including the 1905 one where Frederick William seems to be listed. This does not help!
Thanks again everyone - I am grateful you all seem to be enjoying helping to solve a mystery
