On the basis of the sanctimonious tone taken by Gerald Steinberg MP (the chair of Labour's parliamentary education committee who resigned in protest yesterday) Harriet was presumably supposed to say to her son: "Sorry old love, I know your friends are going to St Olave's and it's a good school, but its selection procedure is against party policy and will cause me and the party no end of trouble if I let you go."
Is not the question, surely, why are the other schools so poor, and what should Labour do about that? It is not Harriet's fault that 17 years of Conservatives who do not know, and care even less, about state-funded education, have left this country with a hopelessly unequal education system. Our schools reinforce our inefficient, socially and economically divided society.
By her action, however, she has drawn attention to the fact that for too long old Labour has colluded with appallingly poor standards in inner- city comprehensives, and particularly in inner London. Our policy is now in shreds.
For too long friends and colleagues have chosen to condemn and drive underground those of us who say these schools are not good enough for our children. This is one of the few areas left in Labour politics where one can be routinely denounced for not being a socialist because you question the current orthodoxy.
But these schools are not good enough for anyone's children. Old Labour pontificates about the importance of supporting local community schools without the slightest notion of the price your children and you may pay to do so.
We give generously of our time to the school, some become governors, others support fundraising and other activities, we help with reading, run clubs after school. But even so, we can still find ourselves defeated and our children's needs not met by teachers coping with large classes, unacceptable numbers of children with special needs, and the problems of mixed-ability teaching under such circumstances. Some of us fly to schools in less poor areas because we can.
If, as Tony Blair says, education is to be the passion of the new Labour government, we need to come clean about the issues we face.
Too many schools are failing too many children. The remedies are many - but the first has to be a commitment to spend money. If we cannot say we will attend to the problems of the many failing schools, we cannot be taken seriously.
We must recognise that all parents have aspirations for their children. They want them to do better than they did, and they feel this with passion.
We must recognise that the middle classes will always have choices, and will exercise them. Our aim must be to get them to choose within the state sector. It means understanding that creating good educational opportunities for all does not mean restricting choices; it means creating more choices to which more parents have access.
As a parent with a son in year five junior school, who lives in Hackney, who is deeply committed to state education (educated in a Yorkshire comprehensive myself), I can tell you there is real anguish involved in these decisions. Will my brightish rather gentle son survive the rigours of my local Hackney secondary comprehensive with its chronic underfunding, overworked and sometimes demotivated staff, children from enormously deprived backgrounds and lousy results? Well, he might, with all of the support we can give and buy for him.
On the other hand, he may not. Given that we have a choice, being mobile, determined and having two incomes, there are other options open to us even in the state sector. We could move house, we could use our skills to lobby and press for him to be in a better school farther away, he could sit exams like Joe Dromey - for which we would have prepared him.
And who would blame us for taking the opportunities for him that we can? You only get one shot at your children's education. In many ways Harriet has done us all a favour.
The writer is director of development of the Fabian Society.