Alan Smithers: How about a lottery for selecting pupils?

What makes a good school? Is it the head teacher, money, facilities, uniforms, independence, a special- ism or a Norman Foster-designed building? Yes, some of those. But, crucially, it is the children who go there, their teachers and the interaction between them. Parents instinctively know this, and it is the most important criterion in school choice.

Allowing parents to choose their children's schools makes good sense, because it tends to lever up quality and standards. But, as the league tables continue to remind us, good pupils and teachers are spread very unevenly across schools. Given a choice, parents will inevitably gravitate towards the schools they perceive to be the best, requiring those schools in turn to select.

The S word carries so much baggage that politicians of whatever hue tend to shy away from it. Neither the Government in its five-year plan, nor the Conservative Party in its recent proposals, really faces up to the issue of how schools should decide between competing parents. Both suggest, rather in hope, that expansion would take care of the problem, but this will in fact just leave more empty places in the less popular schools.

Currently, admission to many schools is by covert social selection. Oversubscribed schools mainly allocate available places to siblings, and then go by distance or religion. All the criteria are open to manipulation - by schools as much as by parents, it has to be said. Parents who can afford to move closest to their chosen school stand the best chance of getting their children in. If the most successful school in a locality is a faith school, canny parents may become assiduous in their worship. Even sibling claims can be contrived, as the definition is far from exact. The net result is that the children of parents who know how to play the system are most likely to get in, and contribute to, the best schools.

This is a lot less fair than selecting on ability. When there were grammar schools across the country, social class had lost its grip on educational performance by the sixth form, and about 70 per cent of Oxbridge entries came from state schools. But the problem was always to devise equivalently attractive schools for those not picked out. The present Government is so hung up on selection by ability that it is further complicating admissions. It splits semantic hairs, so that designated technology schools are allowed to select 10 per cent of their intake on aptitude, but science or maths schools are not, as their specialisms are classed as abilities. Also, the Government has backtracked on the expansion of good schools if they are grammars.

If social selection is now recognised for what it is, and testing for talent is frowned on, what are the other options? Well, one could be price, but this is not used even by independent schools, where selection tends to be on ability. Conceivably, selection could be first-come-first-served, but this conjures up images of parents putting down their child's name in the womb, or Wimbledon-type queues.

But there is a third way, as the Social Market Foundation and Policy Exchange think tanks - from the left and right of centre respectively - have argued: allocation by ballot. Parents, as they do now, would choose a school - but when demand exceeded availability, places would be settled by the drawing of lots.

This gets to the nub of the present weakness. Parents would no longer be able to stack the odds in their favour. All would have equal chances, including those least able to intervene. In time, there would be a more even distribution of children across schools and the genuine prospect of more good schools. It would be straightforward, and the evident fairness would make the disappointment of missing out on the first choice easier to bear.

So why have politicians, especially those avowedly committed to "the many not the few", not seized on the idea? The Government may have calculated that it needs the votes of the current winners. It also seems to be running scared of any headlines along the lines of "Schools admissions turned into a lottery". But it would be a great pity if chasing votes or possible spin got in the way of serious consideration of an approach that seeks to put equality and transparency at the heart of the school admissions process.

The writer is the director of the Centre for Education and Employment Research at the University of Liverpool