19thC Cornish woman hears tapping on her window and believes it portends her mother's death.

The belief that "tokens" or warnings often presaged death was still in general acceptance by 1930.

A story is told of a woman living in St. Ives who, while her mother lay dying, she heard distinct tapping at her window. She looked out of the window but could see nothing, so she dismissed it until a few days later when the tapping occurred again more distinctly. She now thought she was receiving a warning of her mother's death, who in fact died a few days later.

Her neighbors maintained, however, that she had forgotten that she had mended a broken pane of glass with some bread dough when she had no window putty.

I really like the part about forgetting that she fixed a broken pane with some bread.