I had always dreamed of judging a Man Booker Prize. My grandfather, Samuel Hynes, was on the panel in 1981 when he led a successful putsch to give Rushdie’s Midnight’s Children the award, and the Prize has ever since held semi-religious status in the Preston household. In mid-October I came close to achieving this dream. As part of Cheltenham Literature Festival, we reimagined the 1951 Prize (the Booker only began in 1968) before a crowd of almost 400 eager bibliophiles. The shortlist was: Graham Greene’s The End of the Affair, John Wyndham’s The Day of the Triffids, Daphne Du Maurier’s My Cousin Rachel, Anthony Powell’s A Question of Upbringing and JD Salinger’s The Catcher in the Rye (given the rhetorical nature of the exercise, Ion Trewin and John Coldstream, the genii behind the event, fudged the rules a tad: American novels were allowed).

I was to champion The End of the Affair, a book that I had first read as a heart-broken teenager thinking it would help me through some dark days. I didn’t find much solace in the novel: the bitterly sardonic Bendrix was too close to my own angry adolescent self, and the narrator’s reluctant edging towards faith at the end of the book seemed both unlikely and unhelpful. But The End of the Affair stayed with me and I was delighted to re-read this strange tale of faith and fornication.

Chaired by Man Booker head honcho Trewin, I sat on a panel with Natalie Haynes, Amanda Foreman, Erica Wagner and Nicholas Clee. After a spirited debate, it became clear that the prize would come down to a choice between Salinger’s 65-million-selling Catcher and Greene’s brief, angry novel. Eventually, the majority went with The End of the Affair. Nicholas Clee put it best in describing his decision: Greene’s novel is full of flaws while Salinger’s in near-perfect, but the flaws keep us returning to The End of the Affair. Its imperfections are the source of its fascination.

One of the more glaring inconsistencies in the increasingly bilious debate over the 2011 Man Booker is the idea that there is somehow a clear divide between books that are readable and books of high literary merit. What the vitriol-spewers miss is that great literature, from Tolstoy to Fitzgerald to Roth, has always been compulsively readable. Nowhere is this more evident than in the work of Graham Greene. Greene called his thrillers “entertainments”, but he is never merely entertaining.

In a rather bad-tempered review of The Heart of the Matter, Greene’s previous novel, George Orwell lamented the lack of local colour. While the book is set in Sierra Leone, Orwell said the tale of Catholic sin and guilt “might as well have been set in a London suburb.” As if taking inspiration from this barb, Greene did exactly that in The End of the Affair. Taking down his traditional melodramatic scaffolding, Greene gives us a novel that finds its drama not in exotic revolutions or desperate gangsters, but in the almost laughably drab environs of wartime and post-war Clapham Common. It is the very narrowness of focus that gives this novel its intensity and emotional impact.

Greene wrote that authors have an ethical responsibility to write stylish prose: “that’s why no one in my books turns as white as a sheet or trembles like a leaf.” He thought that bad writing “muddies the stream of thought.” The End of the Affair is a scrupulously stylish novel, with a mean, deadpan style indebted to the author’s earlier thrillers. The sparseness of the prose stands in contrast to the hysteria of Bendrix’s voice as the end of the novel and his muted epiphany approach, but also highlights the rare brilliance of Greene’s metaphorical flourishes: when Savage, the head of the detective agency, slides a cliché into his speech “like a thermometer,” or the telephone is “like the mouth of one found dead.”

The End of the Affair explores a love triangle between the author/narrator Bendrix, the saintly Sarah and a jealous God. Like Donne, Greene is obsessed with the friction between the holy mind and the horny body, and believes that “ordinary human love” can exist alongside strong Catholic faith. While Sarah never comes alive on the page, and the religious ending will put many off, the novel’s ambition and the wounded, angry voice of Bendrix make The End of the Affair a novel which may justifiably be called a masterpiece.

It is not Julian Barnes’s Booker-shortlisted The Sense of an Ending that Greene’s novel calls to mind, but rather his previous work, the meditation on death Nothing to Be Frightened Of. Barnes’s rational, intelligent approach to belief is the agnostic mirror of Greene’s unconventional Catholicism. Indeed the quote with which Barnes begins his book – “I don’t believe in God but I miss him” – fits nicely with Bendrix’s indignant “I hate you as though you exist.” The End of the Affair was a worthy winner of our ’51 Booker, a novel that stands the test of sixty years with ease, and that reminds us of the readability of great literature.

Alex Preston is the author of This Bleeding City. His next novel, The Revelations, will be published in February 2012 by Faber&Faber