It is a long time since he stood in front of a blackboard, but Kevin Donnelly still has something of the schoolmaster about him. The air of authority. The pay-attention-please style of conversation. The habit of peering over his glasses, as if keeping an eye on the kids down the back.

Then there is his firm, calm response to disappointing behaviour. When he decides after the initial interview for this story that agreeing to be profiled was a mistake - basically because I cannot be trusted - and informs me that he is withdrawing his co-operation, his tone is as measured and regretful as if he were handing out a Saturday detention.

But we will get to blotted copybooks later. Let's start at the beginning, on the morning I visit Donnelly at home in the quietly prosperous Melbourne suburb of Surrey Hills. I have come to see him for two reasons. First, he is the nation's most controversial education pundit - author of a welter of books, newspaper columns and online opinion pieces in which he contends that the quality of Australian schooling is unacceptably low. His explanation: our classrooms have been taken over by left-wing ideologues whose goal is not to educate children but indoctrinate them. "Learning is no longer valued for its own sake," he writes. "Instead, the role of schools is to liberate students by turning them into new-age warriors of the Cultural-Left."

Donnelly's critics protest that the former English teacher, now in his early 60s, is manufacturing an educational crisis where none exists. Australian students rank well internationally, they say, and if there has been a slight slip down the ladder in recent years, it is a result of inadequate and inequitable funding of schools rather than of any kind of conspiracy. But Donnelly is respected by the federal education minister, Christopher Pyne, who in January appointed him to review the national school curriculum. Donnelly and Ken Wiltshire, a Queensland professor of public administration, were briefed to evaluate the "robustness, independence and balance" of the core courses taught to young Australians. Their report is due to hit Pyne's desk this month and educators across the country are bracing for the impact. "It will be like a small atom bomb going off," one curriculum specialist predicts.

The second reason I am keen to talk to Donnelly is the publication of Taming the Black Dog, a memoir that focuses on the effect on his life of a single catastrophic event. "It is about one person's journey in dealing with loss and depression," he says, as we face each other across his light-filled living room.

Many of Donnelly's ideas about schooling have popular appeal - particularly for parents. He advocates the virtues of mastering mental arithmetic, memorising rules of spelling and syntax, reading Shakespeare and the great novels. Self-expression is all very well, he says, but the best education systems are grounded in rigour and discipline. In 2007, when John Howard launched Donnelly's book Dumbing Down, the then prime minister described him as "a beacon of common sense, exposing many of the fads and politically correct fashions that have found their way into Australian schools".

Donnelly tells me it isn't really the people in the front line he blames for declining educational standards. "I've generally tried to make a point of not attacking teachers," he says. "What I have done is talk about what I call the education establishment." State education bureaucracies, curriculum designers, university academics who train teachers, leaders of teachers' unions - these are the groups that Donnelly excoriates in print. The "educrats" and exponents of "edubabble" are politically motivated, he writes. They have decided that, given "the unlikelihood of ...Australia embracing a socialist revolution, the next best thing is to take control of institutions like schools in order to transform society from within".

Speaking of controlling institutions, Donnelly is billed on the federal education department's website as "executive director of the Education Standards Institute". On his own website, the institute is described as "a Melbourne-based education think-tank", yet Australian Securities and Investments Commission records indicate that it is little more than a trading name for Impetus Consultants Pty Ltd, a company whose sole director and shareholder is Donnelly's wife, Julia. The institute seems to be based in Donnelly's home office. He appears to be the only person on staff.

Does this matter? "It's not actual lying," says Garry Collins, president of the Australian Association for the Teaching of English. "But it's on the continuum there somewhere. It certainly would tend to mislead people who don't know the details."

This isn't the first time Donnelly has been accused of peddling misinformation. His opponents say he is simply incorrect when he contends, for instance, that in our English courses, "literary classics are on the same footing as SMS messages, graffiti and movie posters". Or that in history classes, "students are taught to feel guilty about the achievements of Western civilisation". In Donnelly's opinion pieces, Collins says, "one sometimes gets the sense that truth shouldn't be allowed to interfere with a good story. He does seem to cherry-pick with the research he cites, and ignore other research."

More than 170 senior educators signed an open letter of protest to Christopher Pyne when news broke that Donnelly and Wiltshire had been hired to comb through the national curriculum. A former NSW director-general of education, Ken Boston, said on ABC radio: "Ken Wiltshire is a serious academic - I have a great deal of respect for him. But we need to talk about Kevin.

"Kevin Donnelly is a polemicist. He is not taken seriously. He doesn't engage with reasoned argument or evidence. His views - or rantings, frankly - are well known, and have been disregarded for many years.

His publications are regarded as specious nonsense."

I ask Donnelly how he felt about the reaction. "It did set me back a bit," he admits. "I was a little bit shocked by the degree of vitriol in the personal attacks."

He considered calling his memoir Broadie Boys Do Cry. Donnelly grew up in Broadmeadows, then on the end of Melbourne's northern train line, in a housing commission estate he describes as "a wasteland of brick and cement". He tells me both his parents were alcoholics, and that his father sometimes violently attacked his mother: "The police would come to the house. I can remember, as a little kid, seeing big, strong police barge through the door."

With his elder brother Gordon, Donnelly worked at a milk bar before and after school to earn the money that put food on the table. There was little left for luxuries. "We used to bundle up the newspaper and tie it with string and kick it around because we couldn't afford a football," he says. Not that he and Gordon felt sorry for themselves. "We didn't think we were victims. We kind of believed that if you got on with it, something positive might occur."

Their father left when Donnelly was starting year 11, he says. Soon afterwards, the two boys and their mother were evicted from their house and moved into a small place in South Melbourne. "Mum tried to look after us but she hit the grog. I can remember saying, 'I don't want to be with Mum. I want to be free. I want to be saved.' "

The way Donnelly tells it, the person who rescued him was Peter Mackie, the teacher who had introduced him to Shakespeare at Broadmeadows. He says Mackie arranged for the brothers to start at Melbourne High, a selective boys' school. There, financial support from a past pupils' association allowed them to board with a Mrs Edwards, who treated them as kindly as if they were her own sons. I ask Donnelly what happened to his mother. "Well, she died eventually," he says evenly.

By the time he arrived at La Trobe University in 1970, he had no idea of the whereabouts of either of his parents. "And did I try to find out? Probably not." Then, at some point after he and Julia married in 1974, he got a message that his mother was terminally ill. "So I went to see her and she was on drips and bloated and almost unrecognisable. And didn't recognise me. We found out a day or two later that she was dead." He pauses. "I don't think I even went to her funeral."

His son, James, was born soon afterwards. "And just to jump ahead a bit, we did find out where Dad was. He was in a hospice, dying of cancer. This would be four or five years later. So I did take James, as a little kid, to meet Dad. Just for an hour."

How was that? "Yeah, I mean I'm glad I did it. Because I wanted Dad to know that I had a wife, I had a son, that he had a grandchild. He was happy to see us, but there was no great bond there."

His father had been a member of the Communist Party of Australia, and as a boy, Donnelly enlisted in the youth wing, the Eureka Youth League. In his final year at school, he joined the Secondary Students for Democratic Action. It is difficult to imagine, looking at him now, but at university he wore sandalwood beads and an Afghan coat. He also made a pilgrimage to the Indian ashram where the Beatles had studied transcendental meditation. "I was a so-called radical," he says in a drily amused tone.

Fired with idealism when he started teaching in 1975, he appears to have become slightly disenchanted by the time he arrived at St Helena Post Primary in Melbourne's north-east in the mid-1980s. "He was very keen on teaching but he wasn't so keen on the students," says a colleague from those years. "Because they didn't come up to his expectations. They didn't want to learn, or weren't learning enough. He believed that if everyone was striving hard, they would succeed. And if they didn't, goodbye to them."

For Donnelly, whose parents had always struggled to find the rent, buying a house in the suburbs felt like an enormous achievement. "They make fun of John Howard's white picket fence," he tells me. "But that, to me, epitomised the only thing I wanted." With the acquisition of property came a change of philosophy. "I turned my back on the Left and joined the Liberal Party," he has written. "Why? Looking at my father, I realised the socialist dream, in part, was driven by class bitterness and the politics of envy."

Doug White, a retired education lecturer, got to know Donnelly when the ambitious young teacher returned to La Trobe for post-graduate study. "I liked him," says White, who vividly recalls a conversation in which Donnelly told him he had decided it was time to get with the strength. "He said, 'I want to join the Liberal Party and kick arse.' "

He might have made a good politician. "He loves the whole combat thing," says Simon Marginson, a professor of higher education at both Melbourne and London universities. "For Kevin, everything is valued in terms of 'them and us'."

His attempts to win preselection to stand for parliament failed, but Donnelly's Liberal affiliation has benefited him handsomely since he set up in business as an education consultant. In the 1990s, the Victorian Liberal government led by Jeff Kennett awarded him 14 contracts totalling $540,000. According to an auditor-general's report tabled in parliament, none of the contracts was put to tender. John Howard's federal Coalition government also made use of Donnelly's expertise. Between 1997 and 2003, it paid his company, Impetus Consultants, $119,644 for advice on the development of a civics course for schools, and $56,100 to collect information on "gender-specific and gender-related curricula".

In 2004, he worked as chief of staff to the then federal employment minister, Kevin Andrews, after which he secured a $79,900 government contract to write a report titled Where Do We Stand? The Intended Primary School Curricula Within an International Context. Sydney's Daily Telegraph revealed in 2005 that three pages of the report were lifted directly from his book Why Our Schools Are Failing, and that some other sections - even the 13 pages of recommendations - were paraphrased extracts. Asked by the newspaper about recycling his own material at taxpayers' expense, Donnelly was quoted as replying: "So what? The book was only published last year and the material is very relevant."

Writing in Quadrant magazine in 2009, Donnelly noted that the Grattan Institute, a Melbourne think tank, had accepted funding from Labor governments. Consequently, he said, "any claim to independence has to be taken sceptically. After all, he who pays the piper calls the tune." But he insists he had complete editorial control when the tobacco giant Philip Morris hired him in 1999 to design an anti-smoking program for Australian and New Zealand schools. He says the program, called I've Got the Power, encouraged students to resist peer pressure and make the right lifestyle choices. Even if, in its original version, it did not discuss the adverse health effects of smoking.

Donnelly admits that when Philip Morris approached him, he was "a bit gobsmacked, because why would a cigarette company want to sponsor a program that is saying to young people, 'Don't smoke'?" He says the explanation from Philip Morris executives was that they did not want to attract under-age smokers. "And I took them at their word." (At Sydney University's School of Public Health, associate professor Stacy Carter says tobacco companies started funding youth programs in the 1990s as part of a push to portray themselves as responsible corporate citizens.)

Early on July 14, 2002, Donnelly was woken by a knock on his front door. When he saw the two police officers, his first thought was that James, 20, had got into a fight or been involved in a prank. As he points out, "You don't expect that they're going to say, 'Your son is dead.' "

James had been coming home from a party, walking along the side of a road, when a car hit him from behind. For Donnelly, Julia, and their daughter Amelia, the news was almost impossible to absorb, even when later that day they went to the hospital to formally identify James's body. Donnelly says the reality didn't start to sink in until Amelia, then in year 12, quoted from Hamlet: "Good night, sweet prince/And flights of angels sing thee to thy rest."

The driver had fled the scene of the accident, leaving behind a single clue: the shattered cover of an indicator light. Police reassembled it and, after establishing that it came from a Nissan Navara, issued an alert to spare-parts dealers and panel beaters. "Nothing happened until he had a second accident two or three months later, when he stupidly went and asked for a part," Donnelly says. "So they tagged the vehicle. Then they did phone taps under his house and from his mobile."

In March 2005, the then 33-year-old Phillip Josefski pleaded guilty to charges of failing to stop at an accident, failing to render assistance and conspiring to pervert the course of justice. A charge of culpable driving was dropped for lack of evidence. He was sentenced to 27 months' jail, with a non-parole period of just 10 months, which seemed to Donnelly manifestly inadequate. The Victorian Court of Appeal agreed, increasing the minimum term of incarceration to 18 months.

The relief of James's family and friends turned to dismay when they later learned that Josefski served the last six months in home detention. Donnelly, particularly, was incensed. "As a father who has lost a son, you want some degree of retribution," he says.

He admits in his memoir that he was brought completely undone by James's death. He and Julia had worked hard to provide their children with all the advantages that Donnelly had lacked as a child: a safe home, a loving family, an expensive education. And now this. "During the long nights of troubled and broken sleep," he writes, "I kept repeating Kurtz's cry from Heart of Darkness: 'The horror! The horror!' "

By day, he continued to work as a consultant and to dash off columns warning of the dangers of letting Leftists loose in our schools. "A natural reaction is to put a brave face on," he tells me, "and to show the world that, while things have changed, you can still cope. I suppose my view was, 'Get on with life.' I was busy."

He now believes this was a tactical error, and that grief should be met head on. "The danger is that in not confronting it, you cause a lot of damage."

For quite a while, Donnelly didn't like leaving the house. When he was forced to go out, he wore dark glasses so that no one would be able to look into his eyes. Because of his family history, he worried about sliding into alcoholism: "In my heart, I always knew that was a danger."

Growing up, he had been dimly aware that his father drank out of despair. "He was a train driver and there was talk that he may have had an accident, gone through a crossing, and someone was killed," he tells me. "I suppose his way of coping was to turn to the grog." Donnelly did not want that to happen to him, so he and Julia ended up getting grief counselling. He took solace in his Catholicism, too.

"I don't believe, contrary to the cliché, that there is ever 'closure', " he says. But it seems to him that it is possible to come to an accommodation with the sorrow, and to accept that "part of what we do as humans is to suffer anguish and loss".

The school system isn't the only thing about Australia that Donnelly thinks needs fixing. "Multiculturalism is based on the mistaken belief that all cultures are of equal worth," he has written. "Look at the falling percentage of Australian's [sic] with Anglo-Celtic ethnicity over the last 100 years. The post-war migration program and multiculturalism are designed to breed out Anglo-Celtic, Christian Australia and to reduce us to a nation of tribes."

Still, it seems to Greg Craven, vice-chancellor of the Australian Catholic University - where Donnelly has a post as a senior research fellow - that people make a mistake when they categorise him as "some sort of ideological zealot". Donnelly is actually a bit of a tease, Craven says. "I think he sometimes quite likes presenting himself as a figure of cultural menace and seeing if the media will take him seriously."

Perhaps so, but Donnelly certainly seems concerned about how he will be portrayed in this magazine. The trouble starts a few days after my visit to his home, when the photographic department suggests that he be pictured in a setting suggestive of an old-fashioned classroom - blackboard, oak floorboards, wooden desk, that sort of thing.

"It's a stereotype that paints me as an old-style, out-of-touch, traditional teacher," he complains in an email to me, adding that he is uneasy about the direction this story might take. He wants it to focus on his memoir - "and not my politics or the fact that PM [Philip Morris] was a client". All in all, he thinks it best if he ends his involvement in the project.

I urge him to reconsider, assuring him that he can be photographed any way he likes. In the interest of accuracy, will he at least let me check facts with him? Donnelly is afraid not. He has been set up before, by the ABC and Fairfax (publisher of Good Weekend), he says, and he doesn't intend to let it happen again.

Earlier, at my suggestion, he had given me the names of some friends prepared to be interviewed about him. Now he tells those people not to talk to me. Casting a wider net, I try Christopher Pyne, who doesn't return the call, then Donnelly's fellow curriculum reviewer, Ken Wiltshire. My message to Wiltshire is that I am writing a piece about Donnelly and would be grateful for his input. The email that comes back says: "Kevin are you aware of this. I think it better if I keep out of this. Cheers, Ken."

I email Wiltshire to let him know that he has sent the message to me instead of to Donnelly. After that, I hear nothing from either of the men.