Right. I think I've now made sense of this.

Seems it was the great grandfather that lived in Temperance Cottages. His son, also called William (1904 - 1990) married Phyllis and had a daughter in 1939. In the 1939 register they are living at Carpenter's Cottages in Clearwell, not Temperance Cottages.

Doesn't help finding Kenneth though. I don't know where the information comes from that he was Mable's son. No reason to disbelieve it but I can't find any confirmation of it either. I have Mable working as a servant at Court Farm, Clearwell, in 1911 but nothing after that.