Frank Cornish

Frank Cornish is a Police Officer in St. Mary Mead.

In the novel 4.50 from Paddington, Jane Marple and Elspeth McGillicuddy go to Sergeant Cornish to report that Mrs McGillicuddy had seen a man strangle a woman on a train that was running parallel to hers. Sergeant Cornish is described as a "fresh-faced grave man between thirty and forty". He listens to Mrs McGillicuddy's account, and says that he will have inquiries instituted.

Sergeant Cornish asks Miss Marple where she thinks the body of the murdered woman is, and she says that it must have been left on the train, which is unlikely, as it would have been quickly discovered and reported, or the murderer must have pushed it out of the train onto the line.

Sergeant Cornish later sends a note to Miss Marple saying that full inquiries had been made, with no result. He suggests that Mrs McGillicuddy did witness a scene such as she described, but that it had been much less serious than she thought.

By the time he is involved in the case of the death of Heather Badcock in The Mirror Crack'd from Side to Side, he had been promoted to Detective Inspector. He investigates Heather's death until the county calls in Scotland Yard, and Inspector Craddock is assigned to the case.

After the inquest, Inspector Cornish interviews Arthur Badcock. He also meets Arthur's neighbour, Mary Bain. He notices a watchful look in her eyes, and the slight start she gives when Arthur introduces him. He thinks that she has had a connection with the police at some time, which makes her wary and ill at ease.

Portrayals
Frank Cornish does not appear in BBC's 1987 adaptation of 4.50 from Paddington. There Miss Marple and Elspeth McGillicuddy go directly to the County Police to report the incident to Inspector Slack (who replaces the role of Inspector Bacon in the original novel). In the 1992 BBC adaptation of The Mirror Crack'd from Side to Side, Cornish doesn't appear either. Detective Sergeant Lake and Detective Inspector Dermot Craddock do the investigating in this episode.

Cornish does not appear in NHK's anime adaptation 4:50 from Paddington either. There his role is taken over by the in-that-universe recurrent character of the St. Mary Mead local policeman Constable Hearst.