Pat 
I have seen a property that it could be on google earth, in Garston, but i would like to see it for myself, i will take pics.  
The family does seem to have dispersed around about the same time.
The only info i know about Alfred is that he was a Butcher early on.
I found this
Name    Mr A F Tinch
Birth Date    abt 1887
Age    21
Port of Departure    Delagoa Bay, Mozambique
Arrival Date    23 Jul 1908
Port of Arrival    Southampton, England
Ports of Voyage    Cape Town
Ship Name    Dunluce Castle
Shipping Line    Union-Castle Mail Steamship Company Ltd
Official Number    118490
but then later
Name    A Tench
Estimated Birth Year    abt 1889
Age    32
Port of Departure    Brisbane
Port of Arrival    Sydney, New South Wales
Voyage Arrival Date    18 Aug 1921
Vessel Name    Bardic
Origin Location    Capetown Africa
on the list it shows him as a fireman, if it is him of course, The birth dates are different so they could both be wrong, i am more confident with the first one.
Do you mean William Revelly Tench's Margaret?