In the novel Taken at the Flood, Mrs Leadbetter is Canon Leadbetter's widow and guest at The Stag. She is described as a monumental old lady with iron-grey hair, a flourishing moustache and a deep and awe-inspiring voice. Sixteen years ago, her husband died in Warmsley Vale and is buried there; since then, Mrs Leadbetter has been coming to the inn every year for a month. She greatly disapproves of many things, above all of modern girls and foreigners, and has a go at Poirot when he takes up residence at the inn and enters the room marked 'Residents Only'.
- "'She comes here every year, but of course between ourselves she is rather a trial. She's really frightfully rude to people sometimes, and she doesn't seem to understand that things are different nowadays. She's nearly eighty, of course.'"
(The landlady to Poirot in Taken at the Flood, Book II, Chapter Seven)
She tells Poirot indignantly that on the night of Enoch Arden's murder, at quarter past ten, she saw an indecent girl with a lot of make-up and an orange scarf tied around her head leave the man's room. Mrs Leadbetter states that she heard Arden speak too, telling the girl to get out. This would mean that he was not murdered before that time, giving David Hunter an alibi. Beatrice Lippincott confirms to Poirot that Mrs Leadbetter is of sound mind, albeit "a bit too sharp sometimes".