Spitefully Educated
Kingsley Amis might not have any time for pretentious people who like to show off how smart they are; but there's no getting around the fact that Amis himself is obviously a highly literate dude—Oxford educated, by the way. But some of his most complicated sentence structure can be used to convey humor. For example, he doesn't just say that Dixon woke up with a vicious hangover. Instead, it's:
Dixon was alive again. Consciousness was upon him before he could get out of the way; not for him the slow, gracious wandering from the halls of sleep, but a summary, forcible ejection. He lay sprawled, too wicked to move, spewed up like a broken spider-crab on the tarry shingle of the morning. (6.1)
The contrast between the ordinariness of the situation and the elevated language used to describe it adds to the humor. Another example:
Their relations hadn't altered materially during the ten days or so since the arty weekend. It had taken him the whole of an evening in the Oak Lounge and a great deal of expense and hypocrisy to get [Margaret] to admit that she still had a grievance against him, and more of the same commodity to persuade her to define, amplify, discuss, moderate, and finally abandon it. (8.52)
A bit too complicated than absolutely necessary to describe a kiss-and-make-up scene, but it sure conveys how complicated Jim found it.
Even while he's satirizing the pretensions of people who consider themselves educated and sophisticated, he's still dropping a whole lot of hundred-dollar words.