Red herring is one of the most dominant devices author Roald Dahl uses to craft his short story "The Umbrella Man." A red herring is a type of literary device used in narration to distract a reader from what's really important and make the reader draw "false conclusions" about the outcome of a story ("Red Herring," Literary Devices). To create red herrings in suspense fiction, authors will paint innocent characters as either falsely innocent or falsely suspicious and plant misleading clues.
In his short story, Dahl creates red herrings by describing the elderly man in the story through the eyes of the young, naive, innocent, twelve-year-old protagonist. In her eyes, the man is small, "pretty old," polite, has a jolly-looking pink face, and is a gentleman. The protagonist is convinced he is a gentleman because of what she perceives to be the quality of his shoes, which she describes as being "beautiful brown shoes." She has learned to judge character based on shoes from her mother, who has told her, "You can always spot a gentleman by the shoes he wears."
Though the reader doesn't know it until the end of the story, the reader has many reasons to be suspicious of the young protagonist's assessment of the man. First, since she is only twelve years old, we have reason to question her judgement of his age. Children often think older adults are much older than they really are because children do not yet have the experience needed to judge age. Second, her mother's comment about shoes is really based on such things as expensive brand and materials. All the girl says is that his shows were "beautiful brown"; she is unable to say anything about brand or material because she again does not yet have the experience needed to judge. Therefore, the reader can question her assessment of his shoes. All of these clues--her assessment of the man, her description of him, her judgement of his shoes--are meant to distract the reader from drawing the correct conclusion that the man is not a gentleman and not trustworthy, making them perfect red herrings. But, since they are red herrings, all the reader is at first able to do is see the elderly man from the girl's eyes and be equally convinced of his goodness and of his need for help.
Dahl creates a second red herring through his description of the mother's suspicion of the elderly man. The girl describes her mother as being overly suspicious and overly cold towards people in general. Hence, the reader becomes as equally disgusted as the girl with her mother's suspicion of the man when the reader observes the girl's thoughts:
I felt quite embarrassed by my mother's sharpness. I wanted to say to her, "Oh, mummy, for heaven's sake, he's a very very old man, and sweet and polite, and he's in some sort of trouble, so don't be so beastly to him."
Yet, by the end of the story, the reader realizes along with the protagonist and her mother that her mother's suspicious judgement of the man was correct. Therefore, in making the reader dislike the mother by painting her as overly suspicious and cold, Dahl successfully creates a second red herring.
All of Dahl's red herrings serve to create suspense so that the reader is as equally surprised by the outcome of the story as the central characters and feels equally duped.