Never mind Johnny Rotten, my old history teacher was REALLY scary!

Anybody old enough to remember the unruly days of punk, safety pins and swearwords heard on telly for the first time, should look away now.

For all the noise and rebellion of that era, we went to schools where firm discipline was the norm. Johnny Rotten was scary but Mr Thwackitt the history teacher was a sight scarier.

discipline at the struggling Haileybury Turnford School in Hertfordshire appeared barely to exist on The Secret Teacher (C4), in which businessman Paul Rowlett posed as a classroom assistant, offering extra help to pupils.

Multi-millionaire Paul left education in the nineties with just one GCSE, and the idea was that he might be able to spot disaffected children, the ones who reminded him of himself, and offer the wisdom of experience.

but it’s a wonder that any child can learn at all in a school where pupils appear to spend every lesson chatting among themselves, laughing and lazing.

occasionally a teacher would appeal for calm, like a beleaguered father trying to make a speech at a drunken wedding reception: ‘Excuse me, if I could just have your attention for a moment please . . .’

Paul ambled round the lessons, making new mates like an overgrown schoolboy and gossiping at the back while the teachers were trying in vain to explain algebra or punctuation.

Whenever I see shows like this and comment on the disgraceful behaviour in schools, indignant educators tell me I understand nothing about modern teaching. young people, they say, expect different treatment to the harsh discipline of the Sixties and Seventies.

but I understand this much: when those children look for their first jobs, they won’t be allowed to lark about, mock their bosses, cause disruption and showboat for attention.

Paul knows this himself, because we glimpsed the sales team at work in his office and, of course, every one of them was concentrating on the job.

It seems senseless to let pupils grow up believing they can get away with anything, when they’ll learn a very different lesson once they leave school.

The Secret Teacher pretended that all this could be fixed with a splash of cash from a benevolent plutocrat. With ostentatious generosity, Paul announced donations to the school budget, enough to pay for an extra teacher, and hired a private tutor for one of his favourite pupils.

He offered a job to another lad, a budding entrepreneur, though from what I could see the boy was managing very well on his own.

I suppose this is the blueprint for schooling in the celebrity age: the cultivation of ignorance and a bit of luck for the random few.

Ross Kemp was delving further into the breakdown of the system as he met four young men who all ditched school aged 13 or 14 to become drug-dealers.

Hidden behind masks and sunglasses on Living With Knife Crime (ITV), they told him they could make thousands of pounds a week selling cannabis on the streets. Staying at school seemed to them like a mug’s option.

To protect their profits, they all carried weapons, from kitchen knives to machetes. They assumed their rivals would also be armed. ‘It’s a war, innit?’ grunted one youth.

The casualty figures certainly make it appear to be open warfare: 285 fatal stabbings last year, the worst statistics since records began. Kemp had no solutions, but then he seemed chiefly intent on pulling grim faces and striding purposefully down mean streets.

The obvious cause behind these murders is drugs culture. but the death of discipline in schools must be a contributory factor.