That's so sad Keith.
It makes you wonder though, what led to her drinking in the first place? Probably filthy conditions, maybe post-natal depression, definitely depression, leading to the drink, leading to her becoming an alcoholic. Nowadays she would have had help, and the children (hopefully) would have been placed in foster care until it was safe for them to go back home.
They probably ended up in the workhouse for a while, unless there were other relatives who were willing to house them for a while.
I do hope yr gr grandfather was a better dad second time around, just a shame for the first set of offspring.
Rosemary