Of course these daughters of the townships — whose family income must not, as an entry requirement, exceed £400 a month — are worthy of a school equipped with a theatre, yoga studio and beauty salon. Of course poor girls used to sleeping on the floors of tin-roofed shacks deserve private bedrooms with bathrooms ensuite, filled with fine linens and china, all chosen by the billionaire megastar herself.

For her $40 million investment Oprah could have established ten good schools in Africa — or maybe 40 viable ones — rather than a single, super-deluxe academy. But she wanted to create an institution as exceptional as her pupils, who were chosen not just for their academic gifts but their potential to lead their country.

“They will excel,” Winfrey said, “and pass their excellence on to their families, their nation and our world.” It is hard to think of a more elitist, socially engineered concept than a school designed to prepare talented paupers for political power. But then Oprah, it would seem, is not prone to the queasiness of new Labour — and lately David Cameron — over selective education. For Winfrey, born dirt-poor and black, sexually abused, raised by a grandmother, “education is freedom”.

But what if such a school was founded in, say, inner London, for the very brightest children from the harsh estates of Peckham, Hackney and Paddington. What if those kids, who in Oprah’s words had “a light so bright that not even poverty could dim it”, were removed from grim lives to be initiated into the life of the mind. There they could be instilled with self-esteem, confidence and an absolute sense of entitlement just as the pupils at the leadership academies of the rich: Eton, St Pauls, Westminster, Fettes . . .

What if a parental means test kept this one damn school free from the sharp-elbowed, system-playing middle classes? How many MPs, entrepreneurs, judges, surgeons and film-makers from hitherto unrepresented communities would it produce? What talent would it prevent being tossed away when boredom turns to bad behaviour? How many half-broken lives would it turn around? How many thousands more children would be inspired to work harder to enter its walls?

Of course, unless an Oprah Winfrey is prepared to fund it privately, a London leadership academy could not exist. Even if Oprah, perhaps fancying a peerage, stumped up the required £2 million to found a government city academy, she would be forbidden to select her students by academic ability. Instead she would have to draw children equally from nine bands of ability, from within a system of inner and outer catchment areas so elaborate that it would make confused parents cry. She would not be allowed — as she was in Jo’burg — to interview her potential students, let alone visit their homes and meet their parents. That wouldn’t be fair.

However, Oprah would be permitted to devise some kind of leadership multiple-choice examination and admit a small quota of the children who scored best. But she would have to make the test as idiotic and meaningless as possible.

Last week a friend’s son took a “business and enterprise test” at the City of London Academy in Bermondsey. Assuming that the school was seeking embryonic Alan Sugars, they ran him through some rudimentary capitalist principles: “If you buy 10 lollies for 50p each, how much do you have to sell them for to cover your costs . . .” etc. They needn’t have bothered. The test was in rudimentary IT: how do you switch on a computer, how do you surf the internet, what is a hard drive? Not only would this fail to indicate any entrepreneurial acumen or even basic intelligence, surely it would discriminate against children from families unable to afford a home PC? Anyway, since 3,000 children applied for 160 places they might as well have handed out lottery tickets.

Only when you have, as I do, a child applying for secondary schools (and I admit London is an extreme experience) do you realise the sheer crassness of government bright ideas. Like the very notion of choosing a school because it has been decreed to have a specialism, perhaps in “health sciences” (whatever that is), business or languages.

Most ten-year-olds are fairly unmoulded clay. They have tastes, talents and enthusiasms, but these may pass and others may take their place. State primary-school children are taught little proper science and perhaps no foreign language. Should I sign my son up for a science specialism school because he loves the TV boffins on Brainiac? Does helping out on the Christmas fair cake stall qualify him for a career in business? Parents are being made to feel like Victorians indenturing their tender-aged children into a trade. Private schools don’t have spurious specialisms. They may boast of a particularly fine rugby team or choir but they know what parents require is a school that will fulfil potential in every subject equally and has the facilities to feed a child’s every new passion as it develops.

Whatever the hue of government, a wholesale return to a grammar school system is unlikely. Why would the electorate vote for something that would consign the vast majority of its children to second best? But as a survey by the Centre for Policy Studies showed this week, 76 per cent of British people believe that the brightest pupils should be taught separately and pushed harder. They don’t resent this as elitism: it just makes practical good sense.

The Government realises that the incontrovertible by-product of comprehensive education is reduced social mobility. The income of a family is now a greater determinant of a child’s eventual outcome than it was in the 1950s. Opening up higher education has not led to any more bright working-class graduates, just doubled the number of mediocre posh ones.

Last week’s government wheeze, to award £80 vouchers to the brightest few, shows its acknowledgement of public feeling. But what would that buy? About three hours with a private tutor, a few piano lessons or half a term of Kumon maths. Enough to get a taste for something their parents cannot afford.

Why not instead build a shining city academy that specialises in, well, academia? And invest in some crash barriers to hold back the crowds of parents who will apply.

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