When Mr Milburn talks about school admissions, it is evident that he does not understand how they now work (“Mr Milburn calls for school vouchers”, June 12). He might care to note that New Labour has created many more schools that control their own admissions and can therefore refuse to admit children they would prefer not to teach - so parental choice has to that extent been necessarily frustrated.

It follows that if disadvantaged children are to have a “direct choice” of a publicly funded school, that school must be deprived of any right it may now have not to admit them. This requires legislation, not education credits. That legislation could require oversubscribed schools to admit, say, a given proportion of disadvantaged children before considering the claims of siblings and others that local parents might prefer the school to admit.

If Mr Milburn wants disadvantaged children who have “some ability and have got aspirational parents” to be admitted to a fee-paying school, he is doing no more than to call for a re-run of the assisted places scheme. Has he heard of this scheme? And are not children without aspirational parents the ones that are truly deprived and most need help? Anyway, assisted places schemes do not require vouchers or educational credits or any such administrative clutter. The fee-paying school can simply submit a bill for that child to the Treasury. The suggestion that the money paid to the fee-paying school would be the average cost of that child’s education in a publicly funded school ignores the fact that, with rare exceptions, the cost of educating a child at a successful fee-paying school remains higher.

I’m all for social mobility, but admissions are ground on which angels fear to tread. So politicians of all political persuasions might be well advised not to rush in before having done their homework.

Sir Peter Newsam, Former chief schools adjudicator, director of London’s Institute of Education, and chief education officer, Inner London Education Authority.