Mrs Cocker

In the novel Sleeping Murder, Mrs Cocker is the cook of Gwenda and Giles Reed at Hillside. She almost died after drinking a small amount of brandy, that had been poisoned.

BBC's Miss Marple
In the BBC 1987 adaptation of the novel, Mrs Cocker is portrayed by Joan Scott. In this adaptation, she also begins to feel unwell after the body of Helen Halliday is found at Hillside. She is taken to hospital and later recovers. In this case, she has not been poisoned and the cause of her discomfort is not explained. The illness was probably just a plot device used to remove Giles (who accompanied Mrs Cocker to the hospital) from Hillside. This would leave Gwenda alone at the house for the climactic confrontation Helen's killer.