In the novel Dead Man's Folly, Major Merrall is the Chief Constable of Devon. He supervised Inspector Bland quite closely in the investigations into the events at Nasse House. Merrall had known Connie Masterton, the wife of the local MP, since she was a girl. She was one of the regulars at Nasse House and an organiser of the fete. Merrall could not see how Connie Masterton could be "going around strangling Girl Guides". Nevertheless he insisted that she be treated like everyone else and considered a suspect until ruled out. Merrall tells Bland that Connie Masterton kept calling him and pestering him to use bloodhounds (to search for the missing Hattie Stubbs).
Major Merrall is described as having "irritable tufted eyebrows". He looks "like an angry terrier". However his men all liked him and respected his judgment.