The biographical movie, whether dramatising the life of Abraham Lincoln or an American cargo captain seized by pirates, dominates current cinema. One of the more intriguing examples is Paul Thomas Anderson's The Master, a pseudo-biographical drama in which much of the life of the writer and founder of Scientology L Ron Hubbard is given to a fictional character with a different name.

Amid a torrent of biographical fiction – topped by Hilary Mantel's Thomas Cromwell trilogy – Hanif Kureishi, in his seventh novel, takes an approach more like Anderson's. In The Last Word, Harry Johnson, a young biographer, is hired to write a life of Mamoon Azam, a giant of post‑colonial literature who, after the death of his first wife, now lives in Somerset with Liana, his striking younger new wife.

From the moment that news of the plot got out, literary whispers and gossip columnists suggested the book sas a roman a clef about VS Naipaul, a glamorously remarried Nobel laureate who invited to his Wiltshire retreat Patrick French, whose resulting biography, though apparently approved by Naipaul, presented him as a snob, bigot, adulterer and user of prostitutes.

In pre-publication publicity, Kureishi has played a bat straighter than the favourite openers of Naipaul and Mamoon – both cricket-lovers – on the matter of the novel's possible relation to real people. This insistence on the book's distance from any one author-biographer model is both a legal precaution and an artistic liberation, which permits him to exaggerate enjoyably the fabled depravity of Mamoon, who is rumoured to have been guilty of both murder and devil worship in the past. This fictional Indian author is so evil that he is prone to sitting stroking a cat, like Ian Fleming's Blofeld, in the west country lair where Harry lodges during the research period.

While Mamoon isn't literally Naipaul, it is, in practice, almost impossible for the reader not to impose the face of the author of A Bend in the River on Kureishi's descriptions of the terrifying writer's "hooded eyes" and his nostalgic obsession with the great West Indies cricket teams. Mamoon's conversation about other writers is described, in one of the book's many savagely funny one-liners, as "more like road rage than literary criticism", which sounds very like Naipaul's demolitions of his peers.

Yet, though vulnerable to the charge of being a disguised biographical assassination of Naipaul, The Last Word can also be read as an exercise in disguised autobiographical self-harm. Harry, while described as an English public school toff, often seems to merge with aspects of Kureishi's public persona. Harry's fear that he may be forced to teach creative writing if the Mamoon project fails also plays a humorous one-two with the line in the author's biographical note about being professor of creative writing at Kingston University.

Most writers are prone to unevenness between and within books, but Kureishi's output is so erratic that the reader can sometimes only assume that he has been intermittently coshed on the head, dragged from his writing desk and replaced by an enthusiastic but untutored impostor.

True to this varying form, there are lengthy stretches in The Last Word in which the reader starts to think that the 2014 Man Booker prize judges, if they can find space for an English writer among the threatened American influx, should look no further than Kureishi. These parts of the book teem with arresting aphorisms – "A writer is loved by strangers and hated by his family" – and pithy exposition of character.

There are also frequent enjoyable setpiece scenes, of which the finest is the celebratory dinner with admirers at which Mamoon, like some King Lear who has won the Nobel prize for literature, subjects his guests to increasingly bleak toasts, including "Total self-destruction!" and "Death!"

On other pages, however, the only literary honour that Kureishi seems likely to be claiming is the Bad Sex prize. One of the young women Harry takes as a lover in the country whispers to him, "Your penis is my dog", which makes little sense, except, perhaps, that both have been called a man's best friend.

Indeed, surprisingly for an Oscar-nominated screenwriter and prolific playwright, the dialogue veers between tape-recorder authenticity – Mamoon drawlingly warning Harry that "I hope you're not writing this down in bad English to make us look like mad people" – and unspeakably peculiar locutions.

The biographer, for example, tells his subject, when reminiscing about his own adolescent sex life: "It was a sumptuous pleasure, running into the arms of the women at that age, with many of them being more than nice to me." You wonder if those lovers ever asked him why he sounded like someone put into English by Google Translate, but then this – later in the book – is Harry's chat-up line to a potential sexual partner: "You are a succulent woman, juicy as a dolphin and at your sexual peak too. A woman of unused potential with much life ahead."

Perhaps there is a hidden joke here about a young literary aspirant always sounding like something from a bad book. But, if so, it seems a curious strategy because the more obvious attempts at comedy – and at naturalistic dialogue – are frequently so sharp and entertaining.

Kureishi will be 60 this year and has recently sold his papers to the British Library – both landmarks in a literary life. And, around the diverting games of I-spy-Naipaul in The Last Word, the novel also contains deeper reflections on the businesses of writing, reading and biography, and their fate in what may be a post-literary culture. Although the magnificent comic monster of Mamoon provides much of the book's pleasure, it is finally as significant for what it is about as for whom it might concern.

• Mark Lawson's The Deaths is published by Picador.