Both schools were formed in 1883, under the auspices of Henry Parkes' Public Instruction Act 1880. Sydney Girls in particular had a mission to allow gifted young women to sit alongside their peers at university. That mission is still potent. We still desperately need brilliant and empowered women leaders. But it's not just about societal value. These schools are considered exclusive: elitist hot-houses. In fact they should be seen as Special Needs. Many of these children are ''orchid children'' as identified in recent scientific literature. In a ''normal'' academic environment their brainpower is not a gift but a stigma. The asset becomes a liability. Outside special schools, such children wither and die. In them, they bloom. Orchids need hot-houses. I should perhaps declare an interest here. Both my children have attended Sydney Girls, and I admit to having nightmares as to what we would do if they could not. So I see the problem. But smashing the glasshouses is not the answer. A better resolution would make all schools public. Abolish private schools. Gone. This would free our streets from the three o'clock Porsche-swill under armed guard. It would free all those palatial private campuses for public repurposing - which seems only fair in view of their generous public funding. And it would free said funding as well. You think I joke? Not at all. I have nothing against religion, or for that matter wealth. Broadly speaking, I favour both. But to base educational elitism on these criteria adds no educational value and can only breed a damaging separatism.

Schools, as Henry Parkes memorably said, should be free, secular and compulsory. This is the key to civilisation. Elitism based on academic achievement, however, makes sense. Education is an academic enterprise. To choose and cultivate brainy kids for brain work is like choosing talented runners for athletics training. You want Olympic gold, it's what you do. We need these kids, not just for future Nobel prizes, but to ensure we have a future, at all. Private schools, on the other hand, add little. They build enclaves of privilege for those who need it least. They suck public funding, with three-quarters of non-government schools getting most of their funding from government sources. This is bizarre and unprecedented. And, as theologian Marion Maddox notes in her book Taking God to School, they guise all this as neo-liberal "choice". More compelling still, as corporate lawyer and father of six David Gillespie argues in his new book Free Schools, private schools offer no guarantee of a better educational outcome. You can fork out $150,000 for a child's schooling and essentially get nothing for it.

Private schools may perform decently in league tables but only because they use the fee-hurdle to select for socio-economic status, by far the best predictor of academic success. They further skew their results by giving scholarships to select gifted children who will up their average. In other words, says Gillespie, once you correct for socio-economic advantage, our education system adds no value to what children bring from home. Losing such schools therefore has no net negative. In fact, by flooding middle class energy into the public system, it would bring massive gains. Gillespie points out that the best measure of how much value an education system adds overall is "resilience", that is, the chance a socially disadvantaged child has of performing to his or her full capacity as a human. The world's best education systems - Japan, Finland, Korea - all have a resilience measure over 50 per cent. In Australia it's 30 per cent, and falling. This is bad for us all. Your private school may sit near the top of our league table, but as Gillespie notes, "we are riding a sinking tide, and a sinking tide lowers all boats".

After socio-economics, the biggest single factor in a child's educational success is teacher quality. We all know this from our own experience. We all had that teacher, once or twice. But teacher quality is staggeringly hard to measure, discern or deploy. It is certainly not evident in league tables. But educating, paying and selecting teachers properly - making it a desired and desirable profession, as in Finland - would be a good start. As to inner-city schools, where this debate began, there is no excuse for being suddenly caught short. We've watched the reclaim-the-city movement for a quarter century. When I was first pregnant, everyone said "oh, you'll have to move to the burbs now," as though you couldn't procreate without a lawn-mounted Hills Hoist. That baby is now 24. If we need new public schools, and shrink from sacking the privates, there are obvious public sites. Green Square. Barangaroo. Railway Square, when the bridging project happens. Meantime, New Settlers of Surry Hills take note, the much-loved Alexandria Park community school is still only 60 per cent full. Please tell me your disdain is not due to its high Aboriginal enrolment. Twitter @emfarrelly