At the time of the 1861 Scotland Census Mary Thomson, aged 40, born in Tarbolton Ayrshire, unmarried, sewed muslin worker, and her natural-born son Alexander Ross (6) of Tarbolton, were staying with Mary's mother at 6 Back St., Tarbolton.
At the time of the 1871 Scotland Census Mary Thomson, aged 50, born in Tarbolton, unmarried, was living at 6 Back St., Tarbolton. With her was son Alexander Thomson (16) of Tarbolton, apprentice shoemaker, journeyman.
At the time of the 1891 Scotland Census Mary Thomson, aged 70, born in Tarbolton, single, was staying with her son Alexander Ross and his family at 6 Back St., Tarbolton, Ayrshire.
At the time of the 1901 Scotland Census Mary Thomson, aged 80, born in Tarbolton, single, was with her son Alexander Ross and his family at 6 Back St., Tarbolton.
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Mary Thomson, single, daughter of Neenian Thomson, weaver, deceased, and Elizabeth Thomson M.S. Cowan, died aged 91 years of senile decay, Alexander Ross, son, present.