The dazzling smile that transforms into a thoughtful gaze when that’s more appropriate. The sleek frame encased in expensive tailoring. The good manners. The sincere-sounding tone. The aura of intelligent confidence. It has been rightly remarked that Rishi Sunak is a “Disney prince” version of a politician.

His sensationally rapid ascent has been accompanied by a nagging question, especially among envious Tory colleagues. Is it all too perfect to be plausible? Underneath that polished exterior, surely there have to be some less attractive dimensions – or at least some more jagged edges – to his character?

If there are, they are not to be found between the pages of this biography. That will disappoint the courtiers of raddled old King Boris, who might have hoped for some shocker to tarnish the lustre of the ambitious, much younger and much more popular princeling next door.

Michael Ashcroft is a fan, and he sets the scene for our suave and clever hero by first describing an ancestry populated by a lot of self-improvers who worked themselves up into civil service roles – postmaster, tax official – in India and east Africa when they were still ruled by the British empire. These strivers included the future chancellor’s enterprising maternal grandmother, who sold all of her wedding jewellery to buy a one-way ticket to Britain. Sunak’s mum and dad are, in his words, “classic Indian immigrant parents. They go do a degree that leads to a very specific job and then have security of income – that was their driving mindset.” Yashvir was a family doctor and Usha a pharmacist. They gave their eldest son and his two siblings a comfortable childhood in a substantial family home in the leafier suburbs of Southampton. He grew up in a household where education, hard work and achievement were highly prized.

Ashcroft’s researchers have tracked down a contemporary (there’s always one in this kind of “rising star” biography) who says people had spotted that Sunak was going to be prime minister when he was still at prep school. The schoolmate reports that young Rishi was an “all-round good egg”. The family were affluent enough to send him to Winchester without a scholarship. Contemporaries there remember “a good chap” who became head boy. On this account, the naughtiest thing he ever did was smuggle in a handheld television so that he did not miss the key games of Euro 96. There’s no evidence of the drug-taking that regularly features in the biographies of senior Tories. At Oxford, he secured a first in PPE without leaving much other impression than that he was – but you guessed – “a lovely guy”. The hottest revelation about his university years is that he once took part in an amateur ballroom dancing contest.

His first job was with Goldman Sachs. Junior recruits to the investment bank learned to be very careful about everything they said and the impression they created, because Goldman uses a “360-degree process” in which employees are rated by both their bosses and their peer group. “The result is that you have to constantly manage your brand,” explains someone familiar with the system. “If you upset people or let the team down … you’re toast.” It is one of the book’s more insightful observations that this kind of relentless continual assessment is a useful training ground for politics.

He met his future wife, Akshata, when they were both studying for MBAs at Stanford. “Any ex-girlfriends from his time at Goldman Sachs remain well below the radar,” writes Ashcroft, which is a way of saying that his researchers have failed to unearth any earlier romantic attachments.

I should declare an interest. Some years ago, I resigned as editor-in-chief of politicshome.com when it was sold to Ashcroft, because I thought it inappropriate that the website should be owned by the then deputy chairman of the Conservative party. Still a man of influence in Tory circles, he and his researchers have done a swift and thorough job of rounding up the known facts about the chancellor. There are original nuggets, but the book leans heavily on newspaper reports as well as previously published and broadcast interviews. It is also padded with extracts from a bland column that Sunak writes for a local newspaper and even duller stuff from his personal website. Readers might have been better served had Ashcroft been less eager to whisk out the first biography and given his researchers time to sniff around for more revelatory material.

Important questions go unanswered. Sunak is generally thought to be Westminster’s richest MP, the fruit of having worked for hedge funds for several years after Stanford, but we learn almost nothing about his enriching trading. I’d hoped Ashcroft, himself a very wealthy man, might have been more enlightening about that. Sunak’s hedge fundster years still await investigation.

He clearly has charm, a skill valuable to a politician because most of the breed lack it. Having earned a mint and married the daughter of a tech billionaire, he set out to become a Conservative MP without having done the apprenticeship normally required to bag a safe seat. He had displayed no interest in politics at university. He had not proven his commitment to the Tory cause by being a councillor, a parliamentary aide or being blooded in an unwinnable seat. Yet he joined a fierce competition to represent the bucolic constituency of Richmond in North Yorkshire. This was such terra incognita for a City boy that he made the rookie townie error of trying to look natural in the countryside by buying a pair of blue wellington boots. Yet he persuaded the local association to select him for one of the safest Tory seats in Britain.

Many testimonials to his intelligence include one ally who gushes: “He’s very good at being chancellor. This is his Mastermind subject.” It is claimed that he doesn’t swear – even under stress. “I’ve never seen him snap or lose his rag with anyone,” reports an admiring adviser. “If he does feel pissed off, he just goes quiet.” We’re told that he serves fine wine to guests at his multiple homes, but barely touches alcohol himself.

If this is to believed, Sunak is a unicorn. A schoolboy who no one ever disliked, a hedge fundster who left no one feeling burnt and a politician who doesn’t booze, curse, philander or make enemies.

He’s more of a politicker than he may look. Beneath the suave surface is a tactical calculator of when it is astute to make a splash and when it is smarter to disappear. Though a hardline Brexiter, he ducked the fray during the bitter battles of Theresa May’s time at No 10. He has been quick to suck up personal credit for measures to mitigate the economic consequences of the pandemic, but not so visible when tough decisions have to be defended. He has curried favour with Tory MPs by giving them the impression that he shares their dissent over Covid restrictions without ever publicly arguing the case.

This biography gets more abrasive towards its conclusion, including an enjoyably sardonic chapter about how his image-makers have used social media to promote “Brand Rishi” as if he is an aftershave or a line of aspirational menswear.

The author rightly says we can’t be sure whether this is “Peak Rishi”. Does he have the skills to endure a recession and ascend to the summit of British politics? When recently asked whether he wanted to be prime minister, Sunak replied: “Oh gosh, I don’t have that desire.” So there’s another thing we know he can do with charm: he can fib.

• Andrew Rawnsley is Chief Political Commentator of the Observer

• Going for Broke: The Rise of Rishi Sunak by Michael Ashcroft is published by Biteback (£20). To order a copy go to guardianbookshop.com. Delivery charges may apply