My ability to get to a public library to access their genealogy resources has become somewhat restricted due to illness, so I would really appreciate any assistance at this time.
Everyone, heads up: the above is what I wrote when I started this thread. I'm quite good myself at finding people on the flimsiest of clues and it is onerous to bring researchers in here up to speed; I'm starting to appreciate what I had been warned about with
chemobrain.
If I am coming across as cranky, then I apologise.
Sue,
I notice the slight discrepancy between the birthplace for Jeanie Henry as mentioned in the family notice I had sourced from TROVE and what appears on the marriage certificate itself:
BUCHANAN - HENRY - On 23rd December,1897
at Scots Church, Collins-street, Melbourne, by the Rev. Dr. Marshall, Andrew Buchanan, eldest son of Andrew Buchanan of Blackwood, to Jeanie Henry, youngest daughter of the late William Henry, of Culnady, Co Derry, Ireland.
From the marriage certificate, these are the details about Jeanie Henry:
Name: Jeanie HENRY
Spinster
Birthplace: Culnady, IrelandOccupation: Saleswoman.
Age: 37
Parents:-
Thomas Henry, Farmer
Jane Tomb
The two witnesses were from the Buchanan side who I had researched a few years back.
I caught of glimpse of this record that
suggests this is elder sister of Jeanie, going by the mothers name, which stands out (at least to my aussie eyes).
IG Record 27683
HENRY Margaret Ann William HENRY Jane HENRY nee TOMB Culnady Maghera Loughinsholin Londonderry 1920 - Mrs Margaret Ann Wilson, Culnady, Upperlands, Londonderry. Born about 16 June 1850. 1851 John 4yrs 5mos, James 3, Margaret A. 2.....
http://www.ireland-genealogy.com/view_category/Page-393.html
That's all I can pull up with my old home computer with it's outdated browser and dial-up connection. Cue the violins!

Thanks Sue.
Update:
Just checked the Probate documents that state Mrs Jeanie Buchanan (widow) was living in Douglas-street, Toorak Melbourne, from Sept 1903. This street was also where Toorak College, a boys school from 1874-1918 was situated. Her son, Andrew Henry Buchanan, may been a boarder there?