He prefers, on the whole, wherever possible, if circumstances allow, not to beat about the bush when sharing his thoughts with others. So said, in jest, a friend of Dominic Cummings when asked what information this profile should contain.

For Cummings is one of the most direct people in politics. It is rare for a former special adviser – until January he worked for Michael Gove – to attract the slightest attention. Cummings has leapt to prominence by mounting a frontal assault on Nick Clegg, whom he has accused of being “self-obsessed”, “dishonest” and “a revolting character”.

Nor did the assault end there. It soon widened to include David Cameron, who was blamed for being determined to “prop Clegg up” at the expense of Gove, because Cameron might need Clegg in order to stay in power after the general election in May 2015.

It has been said of Cummings that “you underestimate him at your peril”. He is exceptionally intelligent, without being exceptionally steady: a ruthless man who fights to win and is prepared to risk defeat. If he were a conventional careerist, he could be bought off, or persuaded to be patient in the hope of obtaining the reward of becoming an MP and a minister.

Cummings is more dangerous than that. He is an idealist. When he puts his mind to achieving practical results, which happens to be something he is very good at, he does so because he has ends in view which transcend self-advancement. He takes a dim view of how decisions are taken in government, and believes this can be improved.

Many of his ideas are set out in his long essay Some thoughts on education and political priorities, published last year. In this he declares his ambition for improving education from its present “awful” or at best “mediocre” condition:

We need leaders with an understanding of Thucydides and statistical modelling, who have read The Brothers Karamazov and The Quark and the Jaguar, who can feel Kipling’s Kim and succeed in Tetlock’s Good Judgment Project.

He calls for “an ‘Odyssean’ education so that a substantial fraction of teenagers, students and adults might understand something of our biggest intellectual and practical problems, and be trained to take effective action”. This is not the normal tone of voice in which education is discussed in this country. It is urgent, adolescent, high-minded and shot through with occasional shafts of humility. At one point Cummings volunteers: “There is little original here and the original bits are the least valuable.”

He aspires, he says in another recent piece, to “try to suppress the chaos-inducing entropic forces of Westminster/Whitehall”. He has taken on Clegg for attempting, without agreement or other preparation, to drive through the unfunded “gimmick” of universal free school meals. Cummings has taken this stand because, as he put it on Tuesday of this week, Clegg’s behaviour is “a small example of broader dysfunction (HS2 and aircraft carriers are bigger examples of the broader dysfunction)”, which also demonstrates “why we live in a constant series of gimmicks, cockups, and waste”.

Another special adviser says of Cummings: “He’s mad but very bad – at least, from the point of view of a Liberal Democrat – but I quite like him, though he’s certainly responsible for quite a bit of the naughtiness between Gove and Clegg…He’s obviously motivated by a lack of respect for Clegg, and has a sheer enjoyment of what he’s doing plus a contempt for the Deputy Prime Minister. But I also think he thinks that he’s genuinely making it harder for the Liberal Democrats to try to mess up free schools in particular and autonomy in general. That’s admittedly counter-intuitive, but my sense is that he believes by putting them on the spot he can stop them loading all sorts of undesirable things on the curriculum.”

Clegg himself has dismissed Cummings as “some loopy individual who used to be a sort of back-room adviser”. To attack Gove, and by extension Cummings, appears to Clegg to be good politics. For the Lib Dem polling shows that their voters hate Gove. If these voters knew who Cummings was, one can be confident they would hate him too.

For it is true that Cummings’s personal style is not to everyone’s taste.

Quite a few people consider Cummings to be a complete liability. Andy Coulson, the former director of communications at Downing Street, forbade the employment of Cummings by Gove when the Tories came in to government in May 2010, and managed to keep him out until the end of that year: for Coulson knew Cummings would disobey orders issued by him and others from the centre. Craig Oliver, the current Downing Street director of communications, detests Cummings. Various journalists who have crossed swords with Cummings loathe him. One of them assured me he would never trust Cummings. There is a school of thought according to which Cummings could prove as damaging for the Tories as Damian McBride was for Labour.

Yet friends of Cummings say he is one of the few people they know who is in politics for the right reasons. They insist he is not in it for himself, but because he wants to improve things for other people. To them he is an inspiration.

So who is this figure who arouses such contrary passions? Cummings was born in Durham and speaks with a Durham accent. He is not a gilded member of the patrician circle surrounding Cameron. Cummings’ father was a project manager for the construction of oil rigs and other large structures, and in retirement has bought a farm. His mother recently retired from her work as an educational special needs teacher. Their son went to a state primary school followed by Durham School, a fee-paying establishment founded in 1414. He entered Exeter College, Oxford, where in 1994 he took a First in Ancient and Modern History. His tutors included Robin Lane Fox for Thucydides and Norman Stone for Bismarck.

On leaving university his adventurousness found its first outlet in going to Russia for three years. He helped set up a new airline flying from Samara, on the Volga, to Vienna. The KGB issued threats, the airline only got one passenger, and the pilot unfortunately took off without that passenger. Cummings is a Russophile, speaks Russian and is passionately interested in Dostoyevsky.

In 1997 he returned to London. From 1999-2002 he was campaign director at Business for Sterling, which performed the great service of helping to dissuade Tony Blair from taking Britain into the euro.

Gove, at this stage a leader-writer on The Times, came to a Business for Sterling breakfast at the Royal Automobile Club attended by Rodney (now Lord) Leach, Nick Herbert (now a Tory MP) and Cummings. Gove and Cummings became good friends. A close observer describes Cummings as “one of the few people who can get Michael to change his mind”. The same individual said: “Michael went up in my estimation because he’d employed Dom – someone that mad and off the wall, who can have ferocious temper tantrums, and looks like he’s been sleeping in a hedge.”

Gove, it may be remembered, had in 1995 published a book with the majestic title Michael Portillo: The Future of the Right. Modernisation was in the air, but no one was sure how to achieve it. In January 2002, a few months after becoming Tory Leader, Iain Duncan Smith made Cummings the party’s Director of Strategy: an appointment much welcomed by modernisers.

Eight months later, Cummings resigned. Tim Bale explains, in The Conservative Party from Thatcher to Cameron (Polity, 2010), what went wrong:

The 30-year-old had got up the noses of Tory traditionalists – and not just for his determinedly casual dress-sense and allegedly astronomical salary. Yet far from having ‘captured’ IDS, in the way that some of his enemies claimed, Cummings had come to realise that he was never going to be able to get the Tory leader to go far enough or fast enough and that therefore the modernising project was doomed to a series of half-measures, superficial initiatives, off-message statements and all-too-obvious compromises with those who had never bought in to it.

Half-measures are not Cummings’s thing. Nor did he resort to the usual expedient of an apparatchik who finds himself suddenly unemployed: a job in public relations. Cummings played a full role in the campaign which persuaded his home region of the north-east to vote against Labour’s plan for a regional assembly. He then proceeded to spend two and a half years in a bunker he and his father built for him on their farm in Durham, reading science and history and trying to understand the world.

Gove, meanwhile, was in 2005 elected to Parliament. In 2007, Cameron put him in the shadow cabinet with the education brief. He was now allowed to select for himself a special adviser, known grandly as his chief of staff, and his choice fell on Cummings.

Close observers agree that over the last three years Cummings has been of the greatest importance in getting stuff through the department. As one of them put it: “If you look like you are continually on the point of shouting, and a bit of a nutter, you can be very effective at getting things to happen. And government departments are not usually very good at making things happen. It’s remarkable what you can achieve if you don’t give a f***. Cummings has zero interest in pleasing anyone, even the Prime Minister. He has enough confidence in his own abilities.”

In the Department for Education, Cummings has helped to drive through reform of exams and the curriculum; the free schools programme; and the expansion of academies. Many officials detest him, but he has also a band of loyal and admiring friends. One of them said how amusing Cummings’ sense of humour can be, and described it as dark. His fans praise him as a truly original figure. They point out how keen he became on computers, ensuring that they became part of the national curriculum, and how he pursued his own studies into mathematics and the behavioural sciences. They admit he possesses extreme energy, but deny he is an extremist. They say he is impelled by a desire to improve educational standards for the poor, and by the awareness that global competition will become fiercer. They point to the practical measures he has taken to place subjects such as physics, and Latin and Greek, within the reach of pupils to whom they were denied.

In December 2011, Cummings got married to Mary Wakefield, the deputy editor of the Spectator and daughter of Sir Humphry Wakefield, of Chillingham Castle in Northumberland.

Domestic contentment does not appear to have abated his political ambitions. He still wants to smash up Whitehall and stop politicians and civil servants playing by rules which prevent them from getting anywhere. This kind of radicalism is uncomfortable, which is one reason why it is also rare. Without it, one may doubt whether since 2010, anything much in the Department for Education would have changed.