Shrinking distances for school admissions
Families have to live within 300m of a school to get a place in almost a hundred schools, according to an analysis of school admissions.
The FindASchool website has gathered data on access to places in England's state schools.
It shows the average cut-off distances for oversubscribed schools are 2.3km for primary and 4.8km for secondary.
The study found across the country there were 400 different permutations of entry requirements.
But the number-crunching of admission statistics, which includes some but not all academies, shows this is more of an issue in London than elsewhere.
Across England, just under half of schools, 46%, have more applications than places.
But in London, two-thirds of schools are oversubscribed. And in some boroughs, such as Greenwich, Kensington and Chelsea and Lewisham, 80% of schools lack enough places for the demand.
In Wales, there is less pressure on places, with 13% of schools oversubscribed.
The analysis from the website, part of the 192.com service, also shows how the chances of getting a school place can shrink when there is intense demand.
For 393 schools, pupils will not get a place if they live more than 500m away and for 91 schools, it depended on living within a distance of 300m.
This is again a bigger issue in London, where there are 300 schools where pupils have to live within 750m, compared with 14 in the North East.
The analysis also looked at the impact of a "sibling rule", where schools give priority to the brothers and sisters of existing pupils.
The study found that on average, 5% of places are taken by siblings, reducing the availability of places for others.
FindASchool founder Ed Rushton said that looking for a school place could be very stressful and that parents could face a "confusing array" of different admissions rules.
For individual schools this become "convoluted and opaque", he said, with one primary school in Rotherham having 23 different levels of priority for 16 reception class places.
A Department for Education spokesperson said: "We want every parent to have access to a good school place for their child. Despite rising pupil numbers, 95% of parents received an offer at one of their top three preferred schools this year and we recently committed to investing £23 billion in school buildings by 2021.
"It is for local authorities to ensure they have sufficient school places for their pupils."