The Prime Minister's pledge last week to use new targets for four-year-olds as a basis for measuring children's progress through school has alarmed early-years specialists.
His decision, announced at a meeting of grant-maintained school heads in Birmingham, came only 24 hours after the Government's curriculum advisers were suggesting the new targets would not be used for baseline testing.
The School Curriculum and Assessment Authority fuelled speculation that the policy had been cobbled together by confirming it had yet to be asked by ministers to consider baseline assessment as part of its early-years work.
It emerged last week that SCAA's chairman, Sir Ron Dearing, was not told of the Prime Minister's plans in advance of the announcement. Mr Major told the heads: "When (the pre-school targets) are in place, we will have a sensible basis for simple baseline testing at the start of primary school, which will put in place the foundation stone I want to see for testing at all key stages in school life."
The announcement has convinced some leading early-years specialists that the Government's controversial pre-school voucher scheme is dictating nursery policy, rather than the desire to agree an appropriate curriculum.
Peter Tymms, director of research at Newcastle University's education department, fears that if the targets are linked to funding, it may corrupt the system.
Mr Tymms, whose department runs PIPPS - Performance Indicators in Primary Schools - envisages, for example, pre-schools being promised funding if the children can learn six letters by the age of four. Pre-school workers might then be tempted to cheat to get the money.
Margaret Morgan, chair of the National Association of Head Teachers' early-years working party, said vouchers were also dictating policy on inspections and staff qualifications.
If pre-school records had to be passed to primary schools, judgments on such young children could affect their whole academic careers, says Mrs Morgan, head of Cornist Park primary in Flint, Clwyd.
She worries that some of these judgments will be made by playgroup workers, who, through no fault of their own, are not as qualified as teachers. Parents should write to their MPs about what kind of judgments on their children should be committed to paper, she said.
David Barlett, coordinator for assessment in Birmingham, an authority which assesses children at five to chart their progress, thinks the Prime Minister's pledge could be a recipe for "enormous confusion". He fears that the tests Mr Major wants might be completely different from assessment programmes which are intended to aid children's development.
He concedes that testing and assessment could run side by side but sees technical problems. Baseline tests have to be carried out early, if they are to be of use, yet school admission policies are vary wildly. How could consistent comparisons be made if by the time children in one area had taken a baseline test, children in another area had not even started school?