One of the charges most frequently levelled at the chief inspector by his critics is that he has compromised the independence of his office. The most famous example of this came at the end of last year when he launched a broadside against primary teachers’ alleged devotion to discovery-learning under the imprimatur of Sheila Lawlor’s right-wing think tank, Politeia. This was what provoked one union leader to declare that the Office for Standards in Education had become the Government’s “political poodle”.

Chris Woodhead has dismissed this argument about independence as a futile distraction from the real issues, “an aggrieved mantra that is substituted for any rational engagement”. He has a point. There is another way of looking at Chris Woodhead which says that far from being anybody’s poodle, he is the most powerful figure in education. It frequently looks as if he, rather than Education Secretary Gillian Shephard, sets the agenda on policy, and that it is he, rather than she, who has the confidence of the Prime Minister. More generally, it is clear that he has annexed the high ground on standards to the point where he appears unassailable by politicians or educationists.

Evidence of tensions between Mr Woodhead and the Department for Education and Employment emerged a couple of weeks ago. The Office for Standards in Education published a report on the way the General National Vocational Qualification (GNVQ) was being assessed and marked. While the inspectors were critical, the report acknowledged that the DFEE had already set aside Pounds 10 million in April to address the remaining problems, and the findings were presented constructively. But the press release issued by OFSTED with the report simply highlighted doubts about the credibility of the GNVQ, resulting in a rash of headlines questioning the future of the “vocational A-level”.

DFEE sources admit that there has been “an exchange of views ” between the department and Mr Woodhead about the way the report was presented, while staff at the National Council for Vocational Qualifications were sufficiently outraged by the “entirely negative picture” to send The TES a copy of a furious letter that Mr Woodhead received from their chairman, Sir Michael Heron.

Mrs Shephard and the chief inspector are now frequently seen together in public - a tactic intended to demonstrate their unity, but which also confuses their status. When both launched the report into reading standards in the three London boroughs, it was noticed that it was the Education Secretary who travelled to the chief inspector’s headquarters.

It is also notable that critical reports from Mr Woodhead’s agency tend to bring new powers for OFSTED in their wake. The reading report, for instance, was followed by proposals for OFSTED inspectors to test pupils in the classroom and for an overhaul of teacher training involving a tougher inspection regime.

It is easy to find people - former HM inspectors, headteachers, academics, political advisers - prepared to question the “negative slant” put on OFSTED reports, the reliability of its evidence-collecting methods, the impact of inspections on schools and the way the data are used and interpreted. But few are willing to be named, and there is more to this than just an anxiety to protect their position.

To criticise Mr Woodhead is to ally yourself with the forces of intellectual darkness. He has said repeatedly that his mission is to raise standards, to expose weaknesses in teaching, to keep parents informed, to raise expectations of all children regardless of social background and to emphasise that education should be an intellectual adventure rather than a form of social work. He has declared war on muddy thinking, on teachers who are devoted to the faded dogmas of child-centred education which, he says, are still peddled by the universities. And he puts all these views forward in a lucid, jargon-free style which is attractive to journalists.

What right-minded person would want to be seen to oppose a drive to raise standards? Criticism of Chris Woodhead can thus be safely dismissed as the squeakings of a fusty professional establishment outraged at being exposed to the harsh glare of reality. Mr Woodhead has said himself that he regards all criticism as proof that OFSTED is doing a good job.

The Labour party has so far had little to say about what inspection would look like under a Labour government, beyond arguing for more post-inspection support from local authorities. Labour sources say that it is unlikely that we will hear any criticism of OFSTED or Mr Woodhead before the election for fear that this will imply that the party is soft on standards.

Mr Woodhead was appointed in 1994 on a renewable five-year contract and there has been much speculation on the extent to which he would trim his sails if Labour come to power. Some feel he would not need to, for although he argues for parental choice in his Politeia essay, he has had little to say about the issue that now separates Tories from Labour - selection.

Back in 1994 Chris Woodhead was chief executive of the School Curriculum and Assessment Authority. He was officially appointed chief inspector by a civil service committee, which included Sir Ron Dearing, and Stanley Kalms, chairman of Dixons and a Tory supporter. It is thought that the final choice of Mr Woodhead, rather than Anthea Millett, the other candidate, was made by the then education secretary John Patten. The accepted view is that he was brought in to shake up a system that had become complacent.

John Dunford, president of the Secondary Heads Association, offers another view. “During the 1980s, the Government began to take on a huge number of new powers, and the inspectorate had been encouraged by Keith Joseph to publish inspection reports and undertake more survey reports. The trouble was that the message the Government was getting about the state of the system, particularly from chief inspector Eric Bolton, was often uncomfortable, that there was not enough money, so they shot the messenger and created OFSTED. Under OFSTED the whole focus changed from the inspection of the system to the performance of individual schools.”

Woodhead, whom Mr Dunford describes as “a loose cannon” in the political system, was happier to give advice that dovetailed with government policy. Former senior HMIs allege that inconvenient reports have not been published.

Mr Dunford acknowledges that school inspections under the old system were haphazard and the reports sometimes anodyne, but points out that there was a crucial difference between the reports on particular issues that HM Inspectorate produced and similar reports that now come out of OFSTED.

HMIs would go out to look at an issue, whether it was teaching standards or school buildings, and report on what they found. Now, many OFSTED findings are based on a trawl through reports from general school inspections which are stored in the database. This is why there was concern about the report, published just before last year’s Tory party conference, concluding that class size makes no difference after the earlier years of primary school.

Critics argue that the inspectors had no idea that their reports would be used in this way and say that the conclusion of the class-size report was politically timely.

The report also provoked an argument about how much it would cost to cut class sizes. OFSTED’s estimate of Pounds 250 million (to reduce classes by a three pupils) contrasted with research undertaken for the Labour party by the National Foundation for Educational Research which put the figure at a mere Pounds 60m - although the latter did not include adjustments to accommodation and transport. Doubt surrounds the process by which OFSTED arrived at their figure.

Similar objections were raised about the report on appraisal earlier this year which concluded that it was not working and should be tied more tightly to pay. Michael Duffy, former head of King Edward VI school in Morpeth, Northumberland, says that when his school was inspected, the inspectors hardly considered the issue of appraisal. “I think the evidence OFSTED holds about appraisal is very thin, but that hasn’t stopped it from saying that appraisal is unsatisfactory and needs to be related to pay.”

In the class-size report, OFSTED argues, however, that the fact that inspectors were not aware how their findings would be used makes their evidence more objective because it is unprejudiced. But it gives the impression, says one academic at the Institute of Education, that Chris Woodhead formulates an opinion, then rummages about to find evidence to fit it.

A similar debate surrounds Mr Woodhead’s famous assertion on Panorama last November that there are 15,000 teachers who should be sacked. This figure turned out to be an extrapolation from the number of less-than satisfactory lessons that had been observed in schools inspected (about 5,000 at that time).

The reading standards row in the London boroughs of Islington, Tower Hamlets and Southwark, which blew up before the report saw the light of day, centred on interpretation rather than evidence. The boroughs did not dispute the finding that four out of five seven-year-olds were reading below the average for their age and that teachers were diffident about their skill in teaching reading. But they claimed the report had been rewritten by the chief inspector at the last minute to underscore the most negative findings and that social context had been omitted. They also said that they had got involved on the understanding that the project would be a collaborative exercise to discover which of the methods they were using worked best, and that they had been “betrayed” by the humiliation that followed.

Colin Richards, the only former senior HMI to go public in attacking the chief inspector, has questioned the conclusion Mr Woodhead drew from this year’s annual report that half of all primary schools were unsatisfactory. He drew attention to the fact that the mid-point on the scale inspectors use to grade schools had been changed from neutral to negative for the report, and questioned whether inspectors were aware that they were condemning these schools.

Professor Carol Fitz-Gibbon, at Durham University, argues that the foundation of inspections and OFSTED’s reports is unreliable and that there is no way of checking whether the lessons observed are representative of that school. OFSTED has not demonstrated that different inspectors would come to the same conclusion, she says.

The irresistible rise of Chris Woodhead

Born: October 20, 1946 in London, the son of an accountant in the film industry and a school secretary.

Education: Wallington grammar school, south London (where he is rumoured to have been a rebellious pupil); Bristol University (where he read English, followed by a PGCE) and an MA at Keele University.

Career: English teacher (three posts - Priory school, Shrewsbury; Newent school, Gloucester; Gordano school, Avon) 1969-76; PGCE tutor in English at Oxford University, 1976-82; English adviser, then chief adviser for Shropshire 1982-88; deputy chief education officer, Devon 1988-90 and Cornwall 1990-91; deputy chief executive of the National Curriculum Council 1991, and chief executive 1991-93; chief executive of the School Curriculum and Assessment Authority, 1993-94; HM chief inspector 1994-?

Milestones: 1992 - One of the “three wise men” (the others were Professor Robin Alexander and HM inspector Jim Rose) whose report on primary education questioned some accepted practices, in particular, primary teachers’ devotion to topic work and “topic webs” rather than subject teaching. The report was widely welcomed and accepted.

Worked with Sir Ron Dearing on the revision of the national curriculum - he is credited with writing the English document.

Recreations: Rock climbing, which reinforces his risk-taking image.