I THOUGHT IT BEST TO WARN Miss Coakley about the swearing.

I was about to visit her sixth-form English class with a proof copy of Londonstani — the much-hyped, expletive-laden debut novel from Gautam Malkani, a 30-year-old Financial Times journalist.

She was sanguine: “I’m sure they’ll be fine with that.” But, even with my warning, I am not sure she was quite expecting what her class read out.

My mission was to find out how authentic the book — a no-holds-barred depiction of a gang of Asian teenagers living lives of conspicuous consumption (BMWs, Nokia 6600s, D&G) and petty crime (mobile phone scams) in Hounslow, West London — seemed to a mixed class of 16 and 17-year-olds from Heathland School in real-life Hounslow.

Two weeks before its publication, the book is already notorious for two things: the money and the language.The centre of a huge bidding war at the Frankfurt Book Fair last year, it was bought by Fourth Estate for a six-figure advance (the rumour is £380,000).

Why the fuss? Mainly because Londonstani is written in a head-spinning, expletive-rich mixture of Asian street slang, text-speak, MTV talk and bastardised Punjabi that supposedly reflects the patois of West London Asian gangs. By writing in dialect, Malkani has set himself a tough task; it has worked for Roddy Doyle and Irvine Welsh, but critics had their doubts about the dictated letters in dialect that appeared in Monica Ali’s Brick Lane.

But that is not all. The publisher has hailed the book as “a filthy, unflinching and politically incorrect take on modern Britain”. There is a good deal of violence, pseudo-gangster posturing and mobile phone-worship. Surely Malkani has set himself up for a fall, given his age and job? What does he really know about it? So before dismissing it all as a sub-Ali G spoof, who better to ask whether they really do say things like: “Yeh, blud, safe, innit” in Hounslow than the teenagers themselves? Londonstani’s effect on the A-level class was immediately audible. After only the first sentence there were gasps of surprise and pleasure. Expressions such as “sala kuta” and references to Nike Air Force Ones drew laughter. I was told that “sala kuta” means “bastard dog” (but that you never say it, except as a joke) and that Air Force Ones are the latest trainers.

It turns out that Malkani does know what he is talking about. The consensus from the teenagers was that these words are “real” and this is how Hounslow teenagers speak. Some were at pains to point out that they didn’t use such expressions themselves (although their brothers and cousins did), and some said that even those who do talk like this don’t do it all the time (not in front of their mothers, presumably) but that, overall, Malkani had it spot-on.

However there was also a feeling that it was strange to see the words in print. “He has got everything right,” one girl said. “But it’s too exaggerated and you would never, ever, write these words down.” It seems that fixing the dialect in a book — capturing something by its very nature so fluid and elusive — is almost perverse to them. This is hinted at in the novel when Jas, the narrator, explains gang branding thus: “People are always trying to stick a label on our scene. That’s the problem with havin a fuckin’ scene. First we was rudeboys, then we be Indian niggas, then rajamuffins, then raggastanis, Britasians, fuckin’ Indobrits. These days we try an’ use our own word for homeboy an so we just call ourselves desis." But Londonstani is something special and very funny. There is comedy in Jas’s narration, as he often struggles to suppress his geeky tendencies — “I swear I’ve watched as much MTV Base an Juggy D videos as they have, but I still can’t attain the right level a rudeboy finesse. If I could, I wouldn’t be using poncey words like attain an finesse, innit. I’d be sayin’ I couldn’t keep it real or some-shit” — and in the sheer inanity of comebacks such as another character’s “Wat’s fuckin’ wrong wid dat?” in defence of his aspirations to a career at Heathrow airport. “I’ll be a pilot Top Gun-stylee, innit.”

The dialogue remains surprisingly fresh. But something that the school group picked up on very quickly began to dawn on me only about halfway through. Although Londonstani does not shy away from difficult storylines — painful marriages, cross-cultural violence, religious tension, suicide — something in Malkani’s portrayal is a touch simplistic. It may be a side-effect of the linguistic restrictions that he has imposed on himself, but there is a cartoonish element in the incessant chat, and a distinct lack of character development that makes the more serious threads hard to follow. It is not necessarily an unfamiliar ear that holds you back; you don’t have to be a Dubliner to love Roddy Doyle or a skag-head to enjoy Irvine Welsh. It could have been the same with Londonstani.

But listening to these Hounslow teenagers reading the first chapter demonstrates that Malkani has opted for a high-risk approach that may or may not have paid off. Yes, their tongues slide over the likes of “desi” and “dirrty gora”, but they struggle with Malkani’s insistence on abbreviation — “a” instead of “of”, “yo” instead of “your” — and even, dare I say it, with all the swearing. by Gautam Malkani

Times Recommends

• Simon Kernick's Harrogate festival diary
• The 10 greatest sci-fi films never made
• Europe Between the Oceans by Barry Cunliffe