Professor Tim Brighouse has spent a life in state education. He's London Schools Commissioner, a top adviser to government. No rabid right-winger he. And yet, just recently, he has been reported as arguing that parents of children who do badly at primary school should get a £500 voucher to spend on private tuition.

England and Wales already spends £2bn of its £24bn schools budget trying to tackle the educational needs of poor families. Professor Brighouse wants this to be increased: but of the extra cash he proposes, £500 would go direct to parents to spend privately, a deliberate move to encourage them to take a real interest in their child's education. (And less obviously, perhaps, an admission that the state system is unable to deal with these problems.) As he put it:

The involvement of the hardest-to-reach parents and carers in the form of an 'education extra' voucher would surely help to support the aims of the school and society as a whole not to allow the cycle of deprivation to repeat itself.

That is indeed the problem of state education. But now, it seems, the voucher principle is being accepted at the very top of this crumbling edifice. Sure, £500 to spend as parents choose is not much out of the cost of state education. But it's a start. Now we've all accepted the principle, let's begin talking about how extensive the voucher ought to be.