OK, so the William HENDERSON blacksmith I followed around Ontario and back to Scotland the other day was a red herring.
Today made up for that.
The mysterious Isabella HENDERSON, whom I nearly entirely overlooked because the HENDERSON wasn't very clearly written, living with her (as I now know) cousin William McGREGOR in Galt, Ontario, has solved a genealogical life-long mystery for me, some 30 years on.
What happened to my great great grandfather's brother John (or William for that matter)?
Their sister Margaret was found back in 2006, and redoubled efforts back then failed to find John or William.
However, the answer is that he high tailed it to Ontario from Cadder, Lanarkshire about 1855 with, it appears, most of his family, and followed the family blacksmithing trade.
And I only found his daughter Isabella by complete accident, she is enumerated twice, once with William, and once at home with her parents, also in Galt in 1861.
I've updated the HENDERSON descendant chart with the family I've managed to add to the tree in the last few hours.
Interesting to note that John and Isabella also had a set of twins.
I don't yet know what wife Isabella's surname was as they appear not to have favoured the established church for baptisms, or Tillicoultry, Clackmananshire isn't on the IGI, nor in the OPRs, yet in Canada they are always enumerated as Presbyterian.
Those with ancestry access can follow my trail of source documents for John, including both his 31 March 1901 death cert, AND his entry with his daughter in the 24 Apr 1901 census - didn't he do well.