How did Katy know about the bathtub incident and the severed finger if she wasn't there to witness those events?

I just finished watching "The Futility of the Fly" and what bugged me was how Katy knew about events that happened to the Meldrews when she wasn't around, such as the incident with Victor and Jean accidentally getting into the bath together and the severed finger in their chips.

Surely Margaret and Victor wouldn't have told her as they hardly knew her and she was just their cleaner, not a close friend who they would tell about embarrassing events?