Possibility that John's mother was an Agnes Alexander.
I think this is their entry in 1851:
John Smith 76 Tollkeeper b. England
Agnes Smith 70 b. Ireland
Agnes Smith 26 b. Galston, AYR
Address: Loans, Dundonald, Ayrshire
At least 7 children showing for them in Ayrshire (Kilmaurs) including a James:
Robert 1803
James 1804
John 1806
Elizabeth 1808
Janet 1810
William 1812
Agnes 1813
James's details showing as:
James SMITH
JOHN SMITH/AGNES ALEXANDER
1/03/1804
598/10 303
Kilmaurs
Banns or marriage for John and Agnes show on 11 June 1803 Kilmaurs, Ayrshire.
Monica
I have this information also. There were other children to John Smith & Agnes Alexander - Margaret 1816Ik, Mary Ann 1817, William 1819, Margery 1822.
I think the reason I have misgivings about James' parents as John & Agnes, is because some information doesn't quite tie in. For example in the 1851 census you have sent there, the Occupation for John fits with the death record for James Smith in 1887. Yet in 1851 the age & birth year for Agnes doesn't fit in with her 1813 baptism. I have also found the 1841 census for this family - John Smith, 65, Labourer. Agnes 62. Agnes 19. There is a birth for an Agnes Smith to John Smith & Agnes Hopkins 1822 in Stewarton.
Also, I found an 1851 entry for an Agnes Smith in Paisley High Church.
Robert Laird, 39.
Janet Laird, 40. (Smith)
Robert Laird, 3.
Agnes Smith, 69. Mo-in-Law Born Kilmaurs.
Agnes Smith, 36. Born Kilmaurs c.1815
Margery Smith, 26. Born Kilmaurs c.1825
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1861 Census for Agnes - Back in Kilmaurs, living at Mill Vennel. Aged 80 (1781). Robert Smith 57 (1804) Margaret Smith 37 (1824) Mary Ann Smith 35 (1826) Robert Gallon 61.
The birth years for Margaret & Mary Ann don't fit, but the death record for Agnes in 1862 states -
Agnes Smith, Widow of John Smith a Famer, 6th January 1862 aged 81 at Mill Vennal, Kilmaurs. Parents - James Alexander Farmer & Elizabeth Govan. Informant - Robert Smith, son.
The death record for John Smith 1860 states - John Smith, Farmer, Married (no wifes name) died 28th June 1860 aged 80, at Newhouse Kilmaurs. Son of William Smith (Farmer) & (no mothers name given). Informant - Robert Hodge, Farmer Docksthorn, son in law.
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There is the 1851 census you noted, the occupation for John ties with death record for James.
The 1851 census I found, means perhaps that Agnes was visiting her daughter in Renfrewshire, so John (if the one who dies in 1860) was back in Kilmaurs. So may have to look for him in 1851.
The birth record for Marion Smith in 1855, states her father James (potentially son of John Smith & Agnes Alexander) was 44 so born around 1811 in Newton-upon-Ayr. Which differs from the baptism of James to John & Agnes in Kilmaurs in 1804. However the 1804 birth ties in with the age given on James' death record in 1887. And another spanner in my confusion is that in the 1861 census for James Smith his birth year is given as 1804 but in Ayr, not Kilmaurs.
I wish I could write this more coherently, but my thoughts on it are also muddled. So I apologise.
Keelan