In "the destructors," the most likely reason the boys refer to mr. thomas as "old misery" is because

Most likely the reason is that Mr. Thomas does not interact too much with others and lives alone a solitary life for which the boys refer to him as "Old Misery".
"The Destructors" is a 1954 story written by Graham Greene where "Wormsley Common Gang" is a gang who plan to destroy a two hundred year house. The boys got their gang name from the place where they live.

answer; elasticity of the lungs decreases;

answer; sociological imagination;