From behind his Coke-bottle glasses, the bookseller on the Charing Cross Road focused his magnified eyeballs as narrowly as he was able. "Mordecai Richler?" he said, releasing a frisson of fine dust. "Now there's a name from the past."

For those of us to whom the ghost of Canada's greatest satirical writer remains a biting presence, this was not the most reassuring of statements – especially issuing from a bookseller who himself gave the appearance of having been not so much born as unearthed in some archaeological dig. But such was Mordecai Richler's currency when I checked recently in London – where he lived for two decades and about which he often wrote, largely from the expat's point of view. To wit: none of the used bookshops on the Charing Cross Road carried any of Richler's 10 novels. Ditto his various non-fiction works, or his wonderful Jacob Two-Two children's books. And neither Blackwell's nor Waterstone's nor Foyles had any Richler titles in stock in any of their London branches, except for The Apprenticeship of Duddy Kravitz, of which the flagship Foyles on Tottenham Court Road had all of three copies.

All this has changed as of this month. The big-budget film adaptation of Richler's final novel, Barney's Version, has brought with it an avalanche of new Vintage paperbacks, with Paul Giamatti smirking wryly from the peak of a stacked book-mountain in a chain near you. But don't let that – nor indeed the film's sugary description of itself as "warm, wise and witty" – dissuade you. The film, released in the UK tomorrow, is a competently made drama with some great acting, including a Golden Globe-winning performance from Giamatti. Where it fails is in conveying Mordecai Richler's towering literary presence. And for that, I cannot urge you enough to pick up Barney's Version, the novel – the best of Richler's acidly funny and emotionally moving body of work.

A shambling, jowly figure, Richler was a hellion on the Canadian literary and political scene until his death in 2001, and has proved irreplaceable. Giamatti channels his physical memory as Barney Panofsky: the cardigans, the cigars, the curmudgeon in his slippers. But in the rush to lionise Richler himself (the film is a Canadian co-production, and a piece of national hero-making) the main character is defanged. "Not only does Barney turn out to be a true romantic," gushes the press release, "he is also capable of all kinds of sneaky acts of gallantry, generosity, and goodness when we – and he – least expect it. His is a gloriously full life, played out on a grand scale. And, at its center stand [sic] an unlikely hero – the unforgettable Barney Panofsky."

Retch. The film misreads the novel in two main ways. The movie has its sad moments, but is never dark. And it's occasionally sort of jokey – Giamatti slips on banana peel while running after train, audience cringes for director – but never nearly as acerbic or as funny as the original.

Richler's was certainly a fanged comedy. He regularly drew hysterical accusations of antisemitism for his portrayals of the Montreal Jewish community in which he grew up during the 1930s and 40s. His fervent opposition to blind nationalism – the French-Canadian variety that almost led to the separation of Quebec, and the English-Canadian one that pours money into "Canadian content", regardless of merit – earned him enemies in every province. He was particularly excoriated in Quebec, his home, in part for an article in the New Yorker mocking the "tongue troopers", the provincial government officials who, metric rulers in hand, marched from shop to shop to ensure all French letters on signage were at least twice as large as their English equivalents. He later said of the debate between Canadian federalism and Quebec separatism that it was embarrassing to be on either side. As for the English intellectual world, the Globe and Mail recently pondered why Richler's novels are so rare on Canadian university syllabi – as if their author would ever have wanted them dissected by the academy of which he was so scathing. (Barney's enemy in the novel is a Can-lit superstar, Terry McIver, a pompous, grandiose and unforgivably mediocre talent. The film cuts the character.)

Despite his sharp tongue, Barbara Amiel wrote of Richler in Macleans magazine (where he had a column) that he was never a polemicist, but a satirist – the difference being that a satirist makes his victims laugh. For example, the book takes a swipe at Robert Lantos, the Canadian film and television producer, by having Barney call his schlocky TV production company which (like Lantos did with Due South) makes Americanised TV shows about mounties, Totally Unnecessary Productions. Lantos clearly saw the funny side: he made it a personal mission to produce the Barney's Version film.

If this all makes Richler sound a bit too ... well, Canadian to make much of an impact on UK readers, it shouldn't. True, some of the politics and people he delighted in skewering can be a little obscure, making a Richler novel something of a Joycean maze of references, allusions and quadruple-layered jokes. But, as the writer Adam Gopnik – who grew up across the street from the Richlers in Montreal – points out:

"In many ways, it was the English satiric novelists of that generation who were [Richler's] real contemporaries, far more than the cosmically minded Jewish Americans. He shares with Braine and Amis and Sharpe and Bradbury and Lodge and Simon Gray a balloon-puncturing, self-mocking sound – well-read but frightened of seeming pretentious, allergic to metaphor or self-consciously poetic language, and with them, too, he shared a willingness to render life as it is without trying to make more of it than can be made. It is a form of satiric realism, deliberately circumscribed of obvious ambition – rooted in a desire not to buy into it all, to make fun of petty grandiosity by refusing to be grandiose oneself."

Richler's last novel was also his most universal. Unlike the endless grey parade of books set in historical small-town Ontario that are constantly taking top literary prizes in Canada, Barney's Version struggles with the here and now: with the obsolescence of a man whose political incorrectness makes him a pariah, who destroys the loves that redeem him, to whom the hypocrisy of mocking government subsidies while growing rich on them is not lost. The book grows darker as Barney ages, his Alzheimer's and our increasing awareness of how he has been rewriting his own history gradually raising doubts over the protagonist's central assertion: that he didn't kill his old friend Boogie, a drug addict and symbol of the days before Barney sold out. The film flips this, reassuring us of Barney's innocence, of his goodness. Dana Stevens, reviewing it in Slate, writes: "The story of the older Barney's search for redemption feels forced and maudlin, as if we needed tangible proof that the character was good at heart in order to be moved by his waning days." This is unnecessary: Richler himself conceived of the writer's job as being "a kind of loser's advocate". As Gopnik noted, the author had become inseparably identified with Canada, and with Montreal specifically, "without ever flattering or even saying anything particularly nice about either." Why was it again that all our heroes must be lovable?

Stevens suggests Barney's Version might have worked better as a TV miniseries. I'll go one further. It's already in its perfect form: paper. Let's hope that cheesy Hollywood cover doesn't put anyone off reading one of the best novels by a Canadian ever written.