In the novel Sleeping Murder, Manning is an aged gardener at Dillmouth whom Miss Marple employs at Hillside to supplement the efforts of the regular gardener Foster. Manning, already 75, could not actually have helped much but Miss Marple hires him as a strategic move because he used to be the gardener of Dr James Kennedy and would know about his sister Helen Halliday.
Ever ready to gossip, Manning told Miss Marple, Gwenda and Giles all about the time when he worked for Dr Kennedy. He recalled that Helen was "pretty as a picture" when she first came back from school to live at the house with her brother. She was full of fun and wanted all kinds of entertainment such as going to dances and tennis. He mentioned a strange episode where he had to mark out and prepare a tennis court for Kennedy's house but in the end the court wasn't used very much. For one thing, someone came over at night and shredded up the net. For another, Helen cut herself. Although it was just a graze and Dr Kennedy treated it, the wound did not heal for a very long time.
Manning also talked about Jackie Afflick. Manning said that he was "a bit of nonsense" who had got himself fired from the law firm of "Fane and Watchman". He confirmed that there was a relationship between Helen and Jackie but that Dr Kennedy soon put a stop to it. Afflick left Dillmouth and as far as Manning was concerned, it was good riddance as the town did not need such people.
From the conversation with Manning, it would appear that Dr Kenneday and Helen lived at a house called Crosby Lodge.