Muggles' Guide to Harry Potter/Characters/Mr. Mason

Overview
Mr. Mason is a potential customer of Grunnings, Uncle Vernon's company, who Vernon wishes to impress as part of getting him to purchase a large order of drills.

Chamber of Secrets
Mr. Mason and his wife are representatives of a Muggle company who Harry's Uncle Vernon hopes to snare as clients. In hopes of getting the largest order of drills he has ever received, Vernon coaches his wife and son endlessly for their roles in softening the Masons into placing their order, with methods that are so hopelessly "over the top" that Harry is hard-put to stifle his laughter. Harry, of course, is banished to his room, and ordered to be quiet. The appearance of Dobby, a house elf, results in Harry making some noise which attracts the Mason's attention. Dobby, it seems, wants to prevent Harry from returning to Hogwarts, and in an attempt to force him to stay with the Dursleys, drops Petunia's dessert in the kitchen, before vanishing.

Vernon tries to comfort the Masons following this alarming incident; however, at that moment, an owl swoops in and drops a letter on Mrs. Mason's head. Because she is deathly afraid of birds, she runs from the house, followed by Mr. Mason, who announces as he leaves that he will not be dealing with Grunnings, he has never been so insulted in his life.

Analysis
Though the events surrounding the Masons — the introduction of Dobby, the warning from the Ministry of Magic, the subsequent locking of Harry into his room — are important to our plot, the Masons themselves are not particularly significant; we see little of them, we see almost nothing of their personalities, virtually any Muggle couple could serve here equally well. Their role seems to be to cast additional light on the character of Vernon Dursley, and to provide a reason that would justify his locking Harry up, something that would otherwise be seen as an overreaction by the reader, even given Vernon's character.