Gone are the days when youngsters went to their nearest local primary school then, when the time came, moved up automatically to the local secondary.

The previous government introduced parental choice: people could decide which school they wanted to send their children to. It also began publishing school results tables, so they could compare how well schools in an area were doing.

The result has been an increasing scramble for places at schools which are performing well.

Lawyers were soon involved. The first crucial judgement, known as the Greenwich ruling, went against Greenwich Council in south west London. It established that local education authorities could not stop children travelling to their schools from outside their boundaries.

Then came Rotherham. The Court of Appeal ruled that the local education authority there had acted unlawfully by automatically allocating school places to children living in a catchment area, because that did not give sufficient choice to parents from outside the area.

Preference

The effect is that parents can take nothing for granted: they have to express a preference for their children to attend a particular school - even if they live next door.

Local education authorities still have to make available a suitable school place within a reasonable travelling distance, even if parents have not expressed a preference - but the ones who have done so take precedence.

Sacred Heart High: 350 chasing 150 places

Some areas invite parents to express more than one preference and to rank them in order of priority. The Rotherham judgement took no account of this, but what the government says is that local education authorities can use the ranking if they regard that as "a fair and beneficial way" of deciding who should be admitted to a particular school.

The prime minister's spokesman took the touble to point out that Sacred Heart High School, Hammersmith, was the Blairs' first choice of secondary school for their daughter.

Under the government's draft regulations, which it hopes to have on the statute book in Septmber 2000, all those dealing with admissions - be they local authorities or individual schools - will have to consult each year all those affected by the criteria they use. Disputes will go to an independent adjudicator.

Oversubscription

Sacred Heart High is a state comprehensive within the Hammersmith and Fulham local education authority but is responsible for its own admissions policy because it is a voluntary aided school.

In the case of there being more applicants than places - which is the norm for this school - the top two criteria the governors use are, according to their published criteria:

1. girls from practising Catholic families where there is commitment to the parish community supported by a priest's reference
2. active support by parents/guardians of the aims, values and expectations of the school.

It states: "The school ... will endeavour to preserve its comprehensive character by establishing a balanced intake across the ability range, including those with special educational needs, in the ratio 25:50:25. The means taken to achieve this will include information gained from a non-verbal reasoning test."

Ability no guarantee

This "ability range" relates to assessment tests which all children moving up into secondary schools in Hammersmith and Fulham take, involving such things as numeracy, reasoning and comprehension. The ratio relates to the average performance for any given year - 25% below average, 50% average, 25% above average.

The irony of this type of policy for parents is that a bright child might be excluded because the quota of places for the top band is full, while a less academically able child gets in.

The school regards its natural intake area as being the entire Roman Catholic Westminster Diocese.

The spokesman for the prime minister said: "The Blairs want their daughter to attend a Catholic comprehensive girls' school, of which there are none in Westminster [council area, where they live].

"As the school head and the local education authority have made clear, all the normal procedures were followed in line with the school's admissions policy, and the prime minister's daughter received no special treatment.

"As in any oversubscribed school, there will be disappointed parents and children, but to say that amounts to special treatment for one pupil who is being offered a place is wrong, unfair and without any foundation whatever."