Dear Geoff,
While I cannot help with your dilemma regarding Archibald's father I am very interested in exchanging data with you regarding his mother Flora Mitchell.
Years ago I gave up on this Scottish branch of my family but as recently as this week, I thought I'd look into it again and I think we may possibly be related.
My 3x great grandmother was an Elizabeth Mitchell, who married Samuel Craig in Beith in 1843. In her 1851 census return she claims to have been born in Throushill, Dumfries (transcript only, I haven't seen the original). While Throushill does not appear to exist, Thornhill sounds like a very close match. The fact your Mitchell family appears in both this town and then Beith has to be more than coincidence?! Elizabeth gives her age in the 1851 census as 31 and when she emigrated in 1852, as 29, which also makes her the right age to be the Elizabeth baptised to John Mitchell and Elizabeth Hunter Jul 1821, at Thornhill. I have yet to find her in the 1841 census, though there is a possible entry in Dalry (a town just 4-5 miles from Beith) which could be her, in a household with a Robert Mitchell aged 15 and a Janet aged 2 months.
If she had lived, I would have had a lot more information about her but sadly she died within 12 months of arriving in Australia (or so Samuel claims when he remarried here in 1855), it doesn't appear that her death was officially recorded, so she had either died or run off. The children stayed with their father, so I assume she probably died.
I am related to Elizabeth through her son Hugh Craig. Elizabeth, her husband Samuel and four children (Elizabeth, John, Hugh and Mary) all emigrated to Australia on board the
'Blanche', which arrived in Geelong, Victoria on the 23rd of Nov 1852. Again it appears uncanny that Flora also emigrated here in 1852 (I'd be very interested to know where the family ended up).
Put all together it looks like your ancestor Flora and mine (Elizabeth) are sisters.
I look forward to hearing from you
Regards
Megan