I descend from William's Coutts's son, Alexander Coutts. Hence the obvious name link between the grandson and possible granddad. But then Sarah Douglas's dad was also called Alexander!
Also, just to confuse things, one of the sons of my Alexander Coutts was called Alexander, and one of his sons was too! Obviously an important name in the family.
There are no Isabels/Isobels/Isabellas/Bellas or Elizabeths in my direct bloodline, other than women or the mothers of women the male offspring married. But no daughters of those names. Mind you there are no Sarahs either, and William's wife was Sarah.
The children of the first Alexander (i.e. son of William) were:
(1) Mary Ann - I'm guessing named after Alexander's two sisters who died as children, Mary and Ann
(2) Alexander, Jnr.
(3) Jane - can't see the connection with this name
(4) Jessie - named after her mother, Jessie Birrel Mckay (Alexander Coutts's wife)
(5) Stewart McKay - McKay comes from his mother, not sure where the Stewart comes from
There might be more obvious name links to Alexander Couts and Isabel Leith with the offspring of William's siblings. If he is indeed their 10th child, the earlier siblings might have named their children Isabel first! But I'm not sure I want to go down the very laborious route of exploring all the children of 9 siblings and their marriages, especially when I'm not 100% sure if they are the real siblings.
To me, the 1813 OPR birth cert of William Coutts at Dundee, near Murroes is a strong lead, and the fact that all the other 9 were christened at Murroes, and William was born at Murroes. William's grandchildren and descendants called Alexander is another strong link.
OPR Deaths & Burial search for an Isobel Leith in Arbroath between 1841 (her last census) and 1884 (before statutory death regs.) yielded 2 possible Isobells:
(a) 4 Jan 1844 Isobell Leith, widow of ALEXANDER COUTS MILLER, born in the parish of Arbroath, died in the parish of St. Vigeans, aged 70 of old age. Witnessed by John Coutts.
Laid before Alexander Tyrie* (?) stone, row 26, grave no.5 on 6 Jan 1844
4 years later:
(b) 6 Jan 1848 Isobell Leith - GIRL - so this is a child, not potential "Granny Isobell"
So the first one is possibly William's mother. But all this death reg. tells us is that she was the widow of Alexander Couts (who was a Miller by occupation) and probably had an elder son named John (which fits that list of 10 children).
Found the OPR Death for Alexander Couts too: In the parish of Arbroath, 21 Jan 1832, a Miller, resident at Ferguston, died of a fever, aged 72, married, born at BIRS, laid nearest to Alexander Chrichton's grave (there's that Chrichton reference again!).
Can't find my William Coutts's OPR death, only the one for the Tanner born in Barry, which can't be him. Stat. deaths from 1855 don't come up with anything either.
So, still stuck! But still stubbornly trying!
Thanks for all suggestions, Looby.