It was teamwork with Heywood, she found the marriage and all the children that lead to the 1939 that gave clues to solve. I just looked at what grandchild of Dorcas and James named Sarah that would fit.
To confirm you could get the marriage or one of her children births.
I would look at the 1921 also to get info on Richard Smith I think he may have been a bit older, possibly b 1878, but could be wrong as could not view record, just index.