Johnston family of Dearham

[Helen]

Does anyone have any connections to the Johnston family of Dearham?
John Johnston (1819) married Elizabeth Armstrong, known children were;
William, Thompson, John, Jane, Joseph, Jonathan & Thomas Allan.  I am particularly interested in Thomas.  I have his marriage to
Mary Bigrigg but after the 1901 Census Mary is with someone else, and I'd like to find out, if I could, what happened to Thomas.
I should point out that I don't think Mary was a widow when she 'moved on'.
Helen