By Sean Coughlan BBC News education reporter

The White Paper restricts schools to existing admissions policy

"We are clear that this is entirely different from an 11-plus system that divides children into different schools on the basis of academic ability.

"There will be no return to the 11-plus."

So says the White Paper on England's schools - which, despite promising the opposite, is being accused of being a Trojan horse for the return of selection by ability.

So where is the confusion? Why is Deputy Prime Minister John Prescott being reported as warning of a two-tier school system?

Why are Labour backbenchers threatening to rebel against their own leader's flagship policy?

Much of the current confusion about the meaning of the school reform plans might stem from the smokescreen thrown up by the government's own pre-publicity.

'Buying choice'

Before the White Paper had been published, there were repeated promises of profound and radical change for the school system.

In particular, both Prime Minister Tony Blair and Education Secretary Ruth Kelly talked of the importance of widening access to the most successful schools.

Both promised to change a system in which affluent families could buy their way into the catchment areas of good schools, while children from less well-off homes were denied such a choice.

This raised the expectation that the government was going to seize the politically-sensitive subject of school admissions and address parental demand for places in popular, over-subscribed schools.

But when it came to the publication of the White Paper, the changes to admissions were less dramatic.

Schools would be encouraged to adopt "fairer" systems such as "banding", in which schools take pupils from a range of abilities - but there would be no compulsion, and no withdrawal from the existing code of practice on admissions.

"No one approach towards admissions will work in all circumstances," says the White Paper.

'Fair admissions'

Schools will be "free to use the approach to fair admissions that they think will best meet their local circumstances, as long as it is compatible with the Admissions Code".

Instead the emphasis was on widening access to good schools by increasing the number of options for parents - by allowing good schools to expand, more diversity among types of state schools and encouraging a wider range of providers to set up their own schools.

The biggest structural change proposed by the White Paper was that schools could choose to adopt "trust" status - which would make them independent within the state sector.

And it is this trust school status that has triggered the suspicions that it was going to become easier for state schools to select pupils by ability.

These self-governing schools are promised the right to become their own admissions authority.

New system, old rules?

But along with this promise of independence, the White Paper also retains the restrictions that currently apply - including the block on selection by ability.

Self-governing schools can "set their own admissions criteria, within the law and taking full account of the Admissions Code of Practice".

Resolving this ambiguity over control of admissions is a tough balancing act for the government. Is it a new system if it has to abide by the old rules?

Either trust schools will be independent and could opt for their own solution to admissions problems - which could provoke accusations that it will be a backdoor to selection.

Or, the trust schools concept is not really that radical and offers little more autonomy than at present.

'Specialist schools'

Another unknown quantity in this debate is how many schools are likely to adopt trust status. The theoretical right to control admissions will apply to these trust schools - but there have been few signs so far that schools will rush to sign up.

And while MPs have been warning of the return of selection a large majority of secondary schools in England have already been given specialist status, which allows many of them to select up to 10% of pupils by "aptitude".

The government will argue that its White Paper has never proposed allowing more schools to select by ability - and that suspicious backbenchers are getting hold of the wrong end of the stick.