Three examples of literary devices from the story are hyperbole, metaphor, and simile.
Literary devices are figures of speech that are used by the author to add meaning and interest to the story. They may be used to add description, suspense, or characterization.
A good example of a literary device is the hyperbole used to describe Mike in the beginning of the story. Hyperbole is an exaggeration used for effect. This might also be an idiomatic expression, or in other words an expression used by a group of people.
No one was surprised except Mike, but Mike at the age of nine was surprised by everything. “If you don’t shut your mouth,” somebody once said to him, “you’ll get a frog down it.”
In this case, the idea that if you do not shut your mouth a frog will jump down it is an exaggeration. I do not know if this is a common expression in that part of England, but if it is, it would also be considered an idiom. I can see how it might be. It has an idiomatic quality to it. Either way, it shows how Mike was often surprised, and how Mike kept his mouth closed after this because he was gullible enough to take the expression seriously.
Another example of figurative language is metaphor. In this case, metaphor is used.
He never wasted a word even to tell his name until that was required of him by the rules. When he said “Trevor” it was a statement of fact, not as it would have been with the others a statement of shame or defiance.
The metaphor here is “he never wasted a word.” You cannot literally waste words. Words do not run out, because they are not a finite quantity like money or water. What the author is saying is that Trevor uses his words sparingly, as if he could waste them. He talks very little.
Finally, we have the cousin to the metaphor, the simile. It is an indirect comparison of two things, using the words "like" or "as" to make the comparison.
A smaller bomb and some incendiaries had fallen beyond, so that the house stuck up like a jagged tooth and carried on the further wall relics of its neighbor, a dado, the remains of a fireplace.
In this case, the house is compared to a “jagged tooth.” It really paints a picture, because you can imagine that house standing out in the neighborhood the way a tooth would stand out in a person’s mouth.
All of these examples of literary devices paint a picture for the reader. They create a broader scope for the story, and make it a rich tapestry. In the middle of describing what is going on, the author can sprinkle images like these to clarify exactly what he wants to describe so that the reader can imagine it.