Oh, thank you, lynn. She sounds exactly the age etc., that she should be. She started off as a Johnson, in Wales, may or may not have married an Anderson, but certainly produced a child with that surname, there. She then seemed to vanish, and so did a Charles Tomlinson, from Derbyshire, and I spent literally years chasing every child with approximately the right age and birthplace for her son ... up they popped, exactly the right details, as John and Mary Smith, with son James Henry! They settled in Lancashire, sometimes she was described as his wife, other times as "housekeeper". They had another child, Samuel.
When "John Smith" died, Samuel must've known the true story, he was buried under Tomlinson, and son Samuel took the surname on. All it says on the gravestone is that "Mary" died in 1900 and in Hemsworth. She's not given any surname there, so we surmised that she was not much wanted. I happened upon the "Hemsworth burial plan" topic, and it brought her back to my mind. I think I might now try to find out how long she'd been there, as she wasn't there in 1891 .... alone in the grave sounds as if there was no family there linked to her, perhaps she'd taken a job as a real housekeeper?
Thank you again, I appreciate your effort. Are the relevant records on "Ancestry"?