I was about to flag up an important point in David Cameron's piece today when I spotted that Tim Worstall had beaten me to it. Mr Cameron's piece made this point: Since then, however, we have been overtaken by countries such as Sweden, the Netherlands and some states in the US.

Indeed. And guess what? Sweden, the Netherlands and some states, have voucher schemes.

Some critics of grammar schools and selection have argued that selection and vouchers are incompatible. Nonsense. A voucher doesn't guarantee entry into a school, any more than a cheque book does. It enables it. The purpose of vouchers is to give those who can't afford to write out a cheque the same power as those who can - to take the decision out of the hands of bureaucrats and put it into parents' hands. And, of course, to engender competition between schools, as in the private sector.

There is nothing about vouchers which would, or should, stop schools from deciding their own admissions. Just as in the independent sector today there are some schools which select on the basis of academic ability and some which use other criteria, so with a voucher scheme schools should be free to choose. Choice works both ways.

UPDATE: A correspondent rightly points out that Sweden "expressly forbids selection by ability in oversubscribed schools, so it stands in total contradiction to the grammar school principle." Yes, true for Sweden and I should have made that clear. But not for the Netherlands, as Reform points out:

The displays all of the qualities of school choice – easy market entry, choice of institutions – for which David Willetts and David Cameron have rightly called. Two-thirds of secondary schools are run by independent organisations and funded by the taxpayer according to parental choice.

§ It is also selective. Children are assessed at age 12 through either a test or by teacher assessment. A minority of children are then taught in separate institutions offering either academic or vocational learning. While most children are taught in combined schools, offering both types of courses, most of these are the results of amalgamations of separate vocational and academic schools in the 1990s. In practice the separate buildings still exist, so that children of different abilities are still taught separately in many cases.

§ The result is not the exclusion of some pupils that senior Conservatives may fear. In fact the Dutch system is respected worldwide for its quality and breadth, including its vocational options. In 2004, 55 per cent of pupils took vocational courses from age 14. The system is extremely flexible; in practice many children move from vocational to academic courses. In contrast British vocational education is very weak (and, according to the Education Select Committee last week, the value of the new diplomas is questionable).