Like it or not, however, education has become as much a matter of consumer choice as social benefit. Parents are exercising the freedom to choose what kind to buy as well as where to buy it. And at Pounds 3.95 a go, what Letts is offering is arguably less socially divisive than many of the not so optional extras schools invite parental contributions for.

Assuming that these coaching aids have been bought by parents rather than teachers who, after all, have been far from well-supported themselves, they have plenty of good reasons. They might simply want to know more about the national curriculum and its tests, as the NCPTA’s Margaret Morrissey points out. The whole point of the national curriculum is that it should be knowable and accessible; democratic even, not the private allotment of some secret gardener.

Parents might want to make use of that knowledge. They might be anxious to quell their child’s fear of the unknown (which may well stem from their own). They may want to raise their child’s score on the test by familiarising him or her with the format and style. Some may even want to coach children in the subject matter of the test. Is that so appalling? How does it differ essentially in its good intentions - and potentially divisive effect - from school’s own efforts to involve parents in their children’s’ learning?

Raising expectations is no bad thing, though it can be overdone. But then last week’s report that some junior schools are turning the tests into formal exams shows parents are not uniquely susceptible to that. The re-emergence of 11-plus pressure is not caused by better informing parents about tests. It is the result of selective admissions to secondary schools and selective grouping within them.

Research shows that, whether a school encourages it or not, many parents do attempt to supplement the teaching they imagine children should be getting. HM inspectors findings on the shortcomings of junior schooling suggest this may not be completely misguided.

On the whole, schools recognise the importance of a strong homeschool partnership to reinforce for pupils the value placed on learning. But while many schools say what they want pupils to master at home, not so many spell out how parents can best help, as these guides attempt to do. Letts has not necessarily hit on the ideal parental pedagogy either; its success so far will have had as much to do with its lead in the field and the pricing and marketing of the product as any proven effectiveness.

Instead of questioning whether Letts ought to be doing it, those with the best interests of children at heart should be asking whether this commercial publisher has done it as well as it could and what kind of parental support might help to raise the achievements of all pupils.