One of the difficult things about writing about Jeremy Corbyn is that he is not particularly complicated. He is a Ronseal politician: he does what he says on the tin. Most anecdotes about him are essentially the same: they concern either his politeness, his lack of organisation or his passion for foreign affairs.

The archetypal one is about an organiser in the Islington Labour party, on their first canvassing round since landing the job, dispatching Corbyn to a house containing a large Kurdish family before continuing to direct the rest of the group to other residences in the area. An hour or so had passed before the organiser realised, in a state of some distress, that they had mislaid their MP.

Then Corbyn emerged, having had a cup of tea, a long discussion about the struggle for an independent Kurdistan and gained an intimate familiarity with the exploits of the family’s grandchildren.

He is not someone whose thoughts reward historical study. One official, who worked closely with both Corbyn and Ed Miliband, admiringly describes his mind as “like a filing cabinet”, in which the Labour leader’s opinions are stored unchanged and swiftly accessed when he needs to make a decision or address some neglected policy area. As far as his personal life goes, he is an Englishman of a kind most people are familiar with, which I’ve always suspected is part of his appeal: anyone who has been on a walking holiday, to a lower league football ground or to an allotment has met someone a great deal like Corbyn.

Nonetheless, he is the leader of a movement that has utterly transformed the Labour party and one way or the other will do the same to British politics, so several writers have tried their hand at a study of Corbyn’s life: Rosa Prince’s meticulously researched straight biography Comrade Corbyn, Alex Nunns’s impeccably well-connected inside account of his 2015 leadership campaign, The Candidate, and Richard Seymour’s critical left analysis Corbyn: The Strange Rebirth of Radical Politics. Now Tom Bower, the author of critical biographies of Tony Blair, Richard Branson and others, has had a go with Dangerous Hero.

I haven’t read any of Bower’s earlier work and I’m told that his study of Robert Maxwell is worth reading. On this evidence, quite frankly, you couldn’t pay me to read another of his books. That he refers to Corbyn’s wife, Laura, not by her preferred name of Laura Alvarez, but as “Laura Corbyn” tells you all you need to know about him. There is almost nothing in here that has not already been covered by Prince and you can achieve the same effect by purchasing a copy of Comrade Corbyn and scribbling an insulting adjective every time that Corbyn or another Labour politician is mentioned. Don’t worry that the resulting book won’t make sense: this one doesn’t either.

That Bower refers to Corbyn's wife not by her preferred name but as 'Laura Corbyn' tells you all you need to know

On one page, Bower castigates Corbyn’s failure to scrutinise Islington council, quoting a critical editorial in the Islington Gazette from 1992, saying “not that he cared about such coverage. According to the opinion polls, Labour would win”. A page later, he writes that “the defeat did not surprise Corbyn”. Which is it? Bower bashes Harriet Harman for supporting George Osborne’s welfare bill and criticises Corbyn for opposing it. One can believe that either of these decisions was mistaken but not both.

In 1987, Corbyn is re-elected due to “Labour’s appeal to the middle classes in newly gentrified bits of Islington”, which, as well as being factually contestable as far as the demographic make-up of his Islington North seat goes (it contains some of the most deprived parts of the country), is hard to square with his claim that in 1992 Corbyn “as usual, relied on the immigrant vote” to be elected, one instance in which Bower reaches for a dog whistle when referring to people in the constituency.

The attempts to provide a general history of the times that Corbyn lived in produce a series of jarring handbrake turns, delivered in the same tone of general sneering, which provides an inadvertently comic note. “Corbyn’s lengthy absences from the UK had coincided with the political demise of Margaret Thatcher,” writes Bower, in a sentence that appears to suggest either that Thatcher’s reign would have ended sooner had Corbyn had taken more foreign trips or that there was something untoward going on.

It is just as well that there are inadvertent doses of humour because the attempts to inject it deliberately are a crashing failure. Bower calls Corbyn’s constituency “Antarctica North” in reference to the nickname bestowed upon Corbyn by a Tory MP – “the member for Antarctica North” – for his advocacy of forgotten causes. The joke isn’t funny the first time and repetitions do nothing to improve it.

But, given the rudimentary errors that litter the book, it may be that the running Antarctica North gag is intended to invoke Islington’s sub-Arctic temperatures. Bower refers to one of Corbyn’s few supporters in the parliamentary party as “Cat Stevens, a 30-year-old bisexual republican”. Cat Smith, the MP for Lancaster and Fleetwood, was 29 when she put Corbyn on the ballot and is now 33. Yusuf Islam/Cat Stevens, the singer-songwriter, is 70 and to my knowledge has never expressed an opinion in public about Corbyn or the British monarchy either for that matter.

Bower claims that adviser Seumas Milne began working for Corbyn before he left the Guardian newspaper. Photograph: Dominic Lipinski/PA

Bower speaks of Diane Abbott seizing leadership of the left with her bid for the leadership in 2010, when her candidacy was in part because Harriet Harman and David Lammy, both on the party’s right, wanted to ensure that the field of candidates was not all white men, not because of a struggle for power within the Labour left.

That makes it hard to take seriously the one genuinely new and interesting insight – that Seumas Milne, like Alastair Campbell before him, was advising Corbyn before he had formally made the switch from the Guardian to the Labour party, as it feels likely that Bower has simply got his dates wrong.

Those mistakes make this a double failure. As a biography, it tells us nothing we don’t already know and gets things wrong. As a hatchet job, it is a dismal failure that condemns Corbyn’s decision to skip a meaningless Arsenal match with equal intensity as it does his failure to tackle antisemitism in the Labour ranks. Its only value is as a gift to send to an enemy – and if Tom Bower had confined the readership of this book to Corbyn alone, I for one would be better off.

Stephen Bush is political editor of the New Statesman

• Dangerous Hero by Tom Bower is published by HarperCollins (£20). To order a copy go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £15, online orders only. Phone orders min p&p of £1.99