Recently I completely revised my opinion of a friend who has worn denim and Doc Martens for as long as we've known her. She's the kind of person who believes in saving things: whales, reusable bottles and the Cornish language to name but three.
Just over four years ago she sent us handprinted rainbow cards announcing the advent of Aurora Morwenna Jane. I felt I'd got her family well sized-up, but no. Last week we discovered that little Aurora was being sent to the local private school.
Education is like a little time capsule of truth biding its time. Four or five years after a child is born, the views we may have hidden from others are suddenly revealed. I can think of a couple we know where the wife has worn pearls from the age of 21, and the husband plays golf twice a week, but who sent their son to the local state school.
Until now my position has been cheerfully ambivalent because, by an accident of history, we have ended up with Miranda in the local independent school and John in the state. So I've been able to remain smugly detached from the state vs private argument because we, demonstrably, agree with both.
Straddling the great education divide however has produced two distinct set of friends: The State and The Private and when we discuss education I know each camp means different things by it.
As with all divisions in society myth plays an important part. Many of our state sector friends believe, for instance, that private schools do not prepare children for "life". Yet Miranda's school, the independent one, has a large number of Asian children whereas John's state school class is entirely white. And whereas John tends to be invited to the half-renovated homes of the other middle-class boys in his school, I have collected Miranda from all manner of houses, including the lair of a local gangster made good who had two Rolls-Royces parked in the drive and a swimming pool in the basement.
Many of our private sector friends assume that children who don't go private will have fewer resources at their school. Yet, before we were able to get him into a state nursery, John briefly attended a kindergarten which had virtually no playground and only a few building bricks. When we transferred into the local state school he had computers to draw on and an adventure playground outside.
Everyone likes to feel they are doing the best for their children and this demonising of the other system is a form of reassurance.
The irony is that both groups, state and independent, tend to be split internally. Our private sector friends fall roughly into two groups; those who would no more dream of using the state school than the NHS and those who say they would love to send their children to a state school if only classes were smaller and standards higher.
Our state sector friends divide between ideological supporters of the system and those who could be tempted to go private but just don't have the money. But the tribal divide remains the big one.
For the past two years I've found myself believing that the state system is absolutely right for John but absolutely wrong for Miranda - and vice versa.
After all if I thought otherwise I'd have to move one or both of them, wouldn't I? Now our hand is being forced because we do want to be seen to treat the children fairly. The question now arises, therefore, which school do we suddenly discover was less than ideal after all? Which tribe do we desert?
Adrian Mourby is a writer and producer living in Cardiff