I don't write about the food industry. Or coal mining, or aeroplane construction, or the motor trade - because I don't know much about them. I write about education because it's been at the centre of my life for 48 years and I feel I know it very well. It entitles me, I think, to give an opinion, one informed by intimate experience.
Which is why I become irritated by columnists who get a handout from the Department for Children, Schools and Families, or some uninformed gossip, and make sweeping and often wildly inaccurate statements about the state of our schools. They deem themselves experts just because they've been through the education system at some point in their lives.
Recently, a Sunday Times columnist was commenting on the final report from the Cambridge Primary Review. She told her readers that primary education was in a mess because teachers were trained in outdated orthodoxy and wanted to neglect the "basics", such as phonics and the three Rs. This is not, of course, what the review says at all. Then she made an extraordinary and outrageous statement. "Teachers," she said, "cannot as a group be trusted." This is as daft as Chris Woodhead's assertion that 15 per cent of teachers are useless.
One can only guess at the evidence gathered for her assumption, if any, but the extensive research by Robin Alexander and his team certainly didn't lead to that conclusion. He found that primaries, though under intense pressure in a very uncertain world, were in good heart and highly valued by children and parents. For some children, he said, they formed the only point of stability and positive values in their lives. And having spent my entire career in tough inner-city schools, this has certainly been my own experience.
Just last week, I spent much time with a Year 5 boy who was completely out of control when he transferred to us. His family background is horrendous, but he loves school now and we are desperately trying to give him the basic literacy and social skills he'll need to survive.
Another of our older children tried to take her own life, but the skill, dedication and affection shown by her teachers worked wonders. Yet another, left totally to his own devices once he's out of school, was found wandering the streets late at night. Mum, always well dressed, couldn't have cared less.
But those are just the human pressures teachers face. The torrent of directives from central government and the twists and turns we experience at ministerial whim have to be experienced to be believed. In the first decade of my career, the Plowden report was causing a massive upheaval in primary classrooms. Then came vertical grouping, cascade teaching, the initial teaching alphabet, the integrated day, "real" books, team teaching, cross-curricular education and the national curriculum.
It has never stopped, going all the way from the freeflow classroom, where pupils could choose whatever they wanted to do, to a thankfully redundant "literacy hour" in which teachers were actually given the words they had to speak. I wonder if The Sunday Times columnist is aware that in an eight-year period, 459 documents were issued just on the teaching of literacy.
Throughout my career, I've found very few teachers who aren't dedicated and committed, often against challenging odds. And from 30 years as a head, I know you can achieve exceptional results when you do bother to trust teachers.
But carry on treating them as the Government is doing and we'll end up with an army of disaffected robots. That's not what education is supposed to be about.
Mike Kent is headteacher at Comber Grove Primary in Camberwell, south London. Email: firstname.lastname@example.org.