The title character Jim Dixon is a lecturer in Medieval History at an unnamed provincial university in the early 1950's. He is frustrated by the stiflingly pretentious atmosphere, yet he gamely attempts to win favor with his superior, the absent-minded and boring Professor Welch, in order to hold on to his job, even though he loathes it. He's also involved in a quasi-relationship with a woman he alternately likes and despises. Jim's rage at the pretensions he is forced to observe is relieved by two methods – copious amounts of alcohol and making faces when no one is looking.
The results are almost always hilarious. Amis is adept at painting quick humorous sketches (“a small bullied-looking woman with unabundant brown hair”), but he's at his best in his longer descriptions of Jim's predicaments. I have probably never read a funnier description of waking up with a hangover (“His mouth had been used as a latrine for some small creature of the night, and then as its mausoleum. During the night, too, he's somehow been on a cross-country run and then been expertly beaten up by secret police.”), and it gets even funnier when Jim discovers the damage he has done to his guest room at Professor Welch's house in his inebriated state.
Viewed from more than fifty years later, it's hard for me to measure the impact this biting satire must have had on post-war British society, but it certainly provided me with lots of laughs.