The book is set in Oxford during WW 2. John Kemp is a young man from a small town in Lancashire, who gets a scholarship to attend Oxford. He comes from a working class family and meeting other students from more privileged backgrounds is an eyeopener for John as tries to fit in. He is younger than most of the other students and socially inept and he finds himself in thrall of his roommate Christopher Warner, a lazy, dissipated dilettante.
Almost halfway into the book we finally meet the first "Jill", a figment of John's imagination, a sister invented by him to impress his roommate. He pens letters to her and composes a diary as if she were the writer. He has a very clear picture of this imaginary sister, both of her character and her physical appearance. Imagine his surprise when he comes across a dead ringer for her in a local bookstore. John discovers that this second Jill (actually named Gillian) is part of his roommate's crowd and he becomes infatuated with her. The reader knows this will not end well.
Larkin's introduction to the Faber and Faber edition drew me in. His description of his tutorial mate, Norman, is hilarious and the indolent Christopher Warner shares some of his characteristics. Larkin wrote Jill when he himself was a student at Oxford so he knows his subject well but the novel is uneven. The section about the imaginary Jill drags on and John Kemp is not a likeable character. He scorns the few people who are kind to him and tries to curry favour with the louts who denigrate him. Nonetheless he is such a fish out of water at Oxford that it would be hard not to feel compassion for him. I enjoyed it but I've always been partial to British novels from this era. I may read A Girl in Winter, the novel Larkin wrote the following year.