Moreover, it is still unclear what sort of money will be available, what is meant by "nursery education", or even what is meant by a "four-year-old". For instance, will children be guaranteed a place during the term in which they turn four, the term after, or simply some time before they turn five?
It follows that the number of places needed is also unclear, an issue complicated by the fact that the nation's little ones are hard to pin down: many use more than one type of provision. But most children are catered for in some way. The latest Department for Education statistics show that 91 per cent of four-year-olds are in education - 86 per cent in maintained reception and nursery classes, and 5 per cent in independent schools - although it is hard to tell how many terms of pre-five education some receive.
Add in guesstimates of those who use only playgroups or day nurseries, and there are probably about 5 per cent without any kind of place by one or two terms after their fourth birthday. And some parents of England and Wales' 700,000-odd four-year-olds prefer to keep their children at home.
So there may be very few new places needed at all. And this raises further questions. The Government has promised diversity and parental choice, as well as quality and value for money. Ministers have said much of the promised expansion would be in private and playgroup provision. So will the emphasis first be on raising the quality and staff training levels in existing reception classes, playgroups and day nurseries, as the early years lobby wants? Or will it be on adding places, or will the Government want a shake-up, replacing some of the existing expensive local authority provision with something cheaper from the private and playgroup sectors?
It must also be remembered that, although there are places in education for most four year-olds, these are not spread evenly around the country; Tory-voting rural areas have fewer than urban areas. So perhaps these are the regions which most concern the Government.
Although there has been a great deal of speculation about plans for a voucher system, Education Secretary Gillian Shephard still insists that no funding structure has yet been chosen.
The Government's problem is that the easiest way to fund additional places is through the local authorities, and ministers just do not like the idea. It seems the prejudice stems from the impact of the Children Act, when some private nurseries were forced out of business by overly-rigorous inspection. Grants for Education Support and Training could be the quickest way to fund training. But whatever funding structure is settled upon, whether it is vouchers, a new quango, through the Training and Enterprise Councils, or whether they finally have to use the local authorities, there will need to be a system of ensuring an appropriate curriculum as well as the health and safety of the youngsters.
Low-value vouchers in parents' hands will not do this on their own. One way forward which has been suggested would be for local authorities to draw up development plans in consultation with other sectors, which would cover growth, training and quality assurance, and ensure access to extra funds for all sectors.
The Government faces many quandaries and contradictions within its philosophy as it formulates policy on four-year-olds. One is between its belief in parental choice and its commitment to diversity. What if most parents want nursery classes in state schools, while ministers are determined that there should be more private provision competing to bring costs down? Another is between the pledge of quality and the uncertainty over funding. This is probably one of the key issues which is preventing the Department for Education task group appointed by Gillian Shephard from finalising any proposals.
But quality control will be a central issue. Early this year, the School Curriculum and Assessment Authority and the Office for Standards in Education submitted draft curriculum guidelines to the task group, and they have been kept tightly under wraps ever since. The draft guidelines were based on OFSTED benchmarks for inspecting under-fives provision, and curriculum guidelines in the l990 Starting with Quality report by former education minister Angela Rumbold. It is likely that schools, nurseries and playgroups would have to fulfil all or some of these criteria to get funding, but there are suspicions that they could be watered down according to the money available.
Ensuring quality will not be easy. Early years groups are adamant that training for staff is crucial, and point out there will be capital and start-up costs to create and improve premises before any money can be spent on children's education. At present, there is no national system which covers both curriculum and safety, and education and social services departments each have different rules.
Local authority combined centres, which cover both education and care, are inspected by education and social services departments, as well as OFSTED. They also meet parental wishes for choice within one setting, and can use the resources of two or more departments to good effect.
Maintained nursery schools and classes are inspected by LEAs and OFSTED. Most children in them get half-day education, with high pupil-staff ratios.
Reception classes vary in their child-adult ratios and, most experts complain, in the suitability of their curriculum for four-year-olds. Although many would not meet social services requirements for staff ratios or for premises, they might well meet Government curriculum requirements. Reception classes tend to come out well in OFSTED reports.
Playgroups are inspected by social services, and do not have to meet curriculum requirements. However, the Pre-school Learning Alliance has a voluntary curriculum based on Rumbold's, training schemes and a kitemark for top provision. Money would have to be spent to boost staff qualifications, increase the number of sessions, and often to improve premises.
Day nurseries, public and private, must meet social services requirements for health, safety and child protection, but have no educational requirements. Private nursery schools are inspected by social services under the Children Act, or by OFSTED if they have more than five children of statutory school age.
Pre-prep departments in independent schools who are members of the Incorporated Association of Preparatory Schools are inspected by specialists from the Independent Schools Joint Council accreditation service.
Julia Bennett, of the Association of Metropolitan Authorities, says what is needed is joint inspection by local authority education and social services departments and OFSTED.
"You can say we must have curriculum standards only if you have inspection, " she says. Funding should be dependent on each individual playgroup, nursery class, or other provision being able to show that it meets the requirements, and inspection would ensure that shortfalls were dealt with. What is needed to make quality control work? "More money," she replied.
If places are not of a good standard, parents will not have gained from Mr Major's promise.