He said that he was frequently pestered by spin doctors and special advisers who wanted him to toe the Government line.

His comments will be embarrassing to the Government which has suffered a battering on spin over Transport Secretary Stephen Byers and the “resignation” of two key advisers.

Mr Woodhead, who left the Office for Standards in Education in November 2000, said Conor Ryan, special adviser to David Blunkett, used to telephone him with “suggestions”.

“Conor Ryan...would phone me up, for example, to offer ever so nicely, in his soft Irish brogue, suggestions as to what might be included or changed in speeches and reports,” he writes.

He said Michael Barber, the former head of the standards and effectiveness unit, and Mr Blunkett would also complain if initiatives were criticised.

“Michael Barber... would express his disappointment if we criticised one of his cherished initiatives. Mr Blunkett himself would on occasion fire over a terse little letter.

“Great care was taken of course not to overstep the mark but it was pretty clear which side felt they should be calling the shots.”

His comments come in Class War, a 212-page book to be published on March 14.

In it, Mr Woodhead confesses to having been “naive” to claim, on taking office in 1994, that 10,000 teachers were incompetent and should be sacked.

He said the remark had not been popular with the former Conservative education secretary Gillian Shephard but he stood by it.

“I can understand the argument and it might have been politic to be less provocative. I am nonetheless unrepentant. The longer I did the job the more convinced I became that shilly-shallying gets no-one anywhere.”

Mr Woodhead admits, too, that many reports published during his time as chief inspector were unlikely to offer much of value to schools.

“I couldn’t put my hand on my heart and say that every OFSTED report published in my time sparkled with helpful insights. Too many, if I’m honest, were dull, were written very much to a formula, and were unlikely therefore to contribute much to a headteacher’s thinking.”

Mr Woodhead said the then education department officials were “none too happy” at his appointment after he had claimed in his job interview the right to criticise both teachers and the Government.

“The last thing officials wanted was for an outsider like me to be appointed to a position where they could not pull the strings,” he writes.

Very few are safe from Mr Woodhead’s attacks, which include a litany of traditional targets from council education chiefs to university professors and the teacher unions.

He is more guarded with regard to his successor, Mike Tomlinson. He says Mr Tomlinson’s call for inspection to be done “with” rather than “to” schools suggested that OFSTED was about to become “domesticated” and brought back into the educational establishment.

HOW HE SPILLED THE BEANS

“The DFES is obsessed with processes and procedures. It has embraced every conceivable management fad, but remains damagingly hierarchical and bogged in a mire of non-communication both hopelessly sluggish in its identification of priorities and incoherent formulation of policy.”

“Conor Ryan... would phone me up for example to offer ever so nicely, in his soft Irish brogue, suggestions as to what might be included or changed in speeches and reports.”

“Michael Barber... would express his disappointment if we criticised one of his cherished initiatives. David Blunkett himself would on occasion fire over a terse little letter.”