Ah, the authentic note of Sir John Harvey-Jones when faced with a duff business plan. Except that this wasn’t a business plan but an initiative to rescue a sink school, and the executive he was confronting was the head.

In Wednesday’s Troubleshooter programme on BBC2, the former head of ICI turned his attention to the English education system. As usual, he laid cheerfully into people and institutions which, for reasons best explained to a psycho-analyst, had agreed to submit to The Treatment.

First we were given a chance to do a bit of psycho-analysis ourselves. As Sir John stood in front of his old prep school in Deal, to which he was sent from India at the age of six, the florid 70-year-old in the red jumper disappeared and was replaced by the image of a pale, thin boy in a striped PE kit. He was beaten and constantly bullied and remembers wanting to - and trying to - kill himself. “I suppose a lot of little boys do that.”

Not hard to understand why he should want to do a spot of bullying himself later on. Nor why, given the television-sent opportunity to demolish his old school building, he should laugh manically and aim at the headmaster’s study.

His aim was not to take a trip down memory lane but to discover why British children seem to emerge from school less qualified than their economic competitors.

First stop was Lawrence Weston comprehensive in Bristol, “academically speaking, right at the bottom of the heap” and with numbers down from 1, 100 to below 300.

Motivating pupils was the problem, said the head, Chris Lindup, who had the look of a defeated man. Was it, wondered Sir John to himself, or could it be the school was just getting duff kids? But after a few minutes’ banter with some sparky 11-year-olds in the cafeteria, he concluded the kids were “bright as a button”. Cut to Sir John talking to confused 16-year-old leavers, with no idea what they wanted to do - and no qualifications to do it anyway. What had gone wrong in between?

He concluded, after talking to a couple of teachers and listening in to a maths class (“Surely 14-year-olds are capable of more than this?”), that the staff were “a defeated army”, and there was a very big gap between what the head thought could be achieved and the expectations of the rest.

Such breezy judgments seem highly superficial. And yet you knew he was right, and that 10 HMIs crawling over the school for 100 person-days would have reached a similar conclusion, but less pithily expressed.

“You have to be more explicit,” he told Chris Lindup: get the school in uniform within six months, have a group photograph and “a bloody party”; set objectives, like saying that within three years the school would no longer be academically bottom of the heap. But he hinted darkly he was not sure the head could take all his staff with him.

Tough, this trial by television. A year later, when Sir John returned, academic results had improved by 300 per cent and the maths teacher had taken early retirement.

In between, he darted into a public school to see if there was hope for Britain there. Clifton College, with its choristers, cloisters and competitive sports, was almost a caricature of what a public school should be, Sir John remarked. Sadly, their brightest and best, assembled for him in the library, took a dim view of industry.

But Mrs Thatcher destroyed our manufacturing base, it’s a thing of the past, they said, while Sir John clutched the table in disbelief, muttering that the world’s fourth largest exporter must be exporting something.

Anyway, they said, industry didn’t interest them intellectually, its image was of “legions of people designing toilet lids or whatever”. So what did interest them? “I’m personally interested in diplomacy, especially in the Pacific rim”.

Sir John, somewhat shaken by this encounter, needed cheering up. So he headed off to the Garibaldi School in Nottinghamshire, which he has been helping to transform over the past six years. Here all was buzz and building work; pupil numbers had doubled; the head of maths had a gleam in his eye. Sir John even found some engineers.

He ended with the teacher training system and an anecdotal approach: a conversation with his granddaughter Abigail and two friends training as primary teachers. At this point, there was a suspicion that Sir John was speaking the Government’s lines. They had learned all about racism and gender at college, said the girls, but not really how to structure a lesson.

His conclusions? He is more optimistic than he was, but he still thinks we’re wasting far too much talent. The problems are our divisive education system, “historic class baggage”, “bombed-out teachers” and not enough really good leaders - but, above all, the British reluctance to push everyone to do their absolute best.

Well, yes, but do we have to send Sir John into every sink school to do something about it?