Lack of intellectual freedom, rather than low pay and high workload, is turning the brightest undergraduates away from teaching, Philip Pullman, the prize-winning author says.
Speaking at the Oxford Literary Festival, this week, Mr Pullman, a former teacher, said that talented young people were no longer attracted to the profession. "The most able people, on the whole, don't go into teaching, and those who do are not distinguished by their intellectual curiosity," he said.
"Their kindness is undoubted. You could warm your hands on their good intentions. But after a while in their company, you long for an astringency of mind."
He told The TES that fear now dominates the classroom: fear of exams, of league tables and of school inspections. Teachers are worn down by the need to deliver a government-imposed curriculum.
"Teachers are not trusted to teach," he said. "They're nagged, they're controlled, they're harassed. They have to be inspected all the time. Set them free. Trust them."
Teachers are limited by the failures of their own education: "These young people are tigers, born in cages and kept caged, until they think that being caged is the natural condition.
"But the same people in 20 years' time will be full of curiosity, full of knowledge and full of passionate desire to do things with it. It's just a question of growing up."
Mr Pullman, 56, spent 12 years as a teacher in Oxford middle schools. He then became an education lecturer at Westminster College, Oxford, before leaving the staffroom to write full-time.
But his years at the chalkface taught him that the self-assurance to think outside the standardised test can only come with age.
Ideally, he says, no under 35s should become a teacher. The preceding years should be spent gaining life experience, so teachers should wait to enter the profession.
"It's like this gap-year business, which does such good things for university students. They should have a gap of 15 years before they start teaching. Any human experience is useful for a teacher. Travel, or learning a profession. Get married. Have children. That all gives you a solid base to draw on."
He cites his own teachers as examples. One commanded a tank at El Alamein during the Second World War; another was part of the Arctic convoy.
"These were men of real stature, who had dealt with life and death. They had real stories to tell.
"I don't think the government would have tried it on with them. They were bigger people. We need big people."
John Bangs, head of education for the National Union of Teachers, agrees that older people, with greater life experience, should be encouraged to enter teaching. But, he added, the best schools offer a broad mix of staff experience.
He said: "Tests and targets are an unnecessary constraint, and they are a factor in putting off people. But I think we've got lots of very sharp, enthusiastic young people coming into teaching.
"Everyone's very good at making policy out of their own experiences. But there shouldn't be a formulaic approach. It should be an all-embracing profession, where young and experienced people all have their place."
Philip Pullman has published 38 novels, including His Dark Materials trilogy, which was acclaimed by both children and adults.
In January 2002, The Amber Spyglass, the final novel in this trilogy, won the Whitbread literature prize: the only children's book to win this award.
Recruitment improves, 9