Head teachers say the confusion this year is the worst they have faced. As parents hedge bets with multiple applications it is impossible to plan classes and budgets.
Teaching unions insist the mad dash results from reforms like the publication of exam league tables intended to increase parental choice. Parents have submitted false addresses, others are renting temporary accommodation within sought-after catchment areas; others have invented older children to exploit a rule giving preference to siblings.
The confusion is exacerbated by a High Court ruling five years ago allowing parents to apply to schools outside their boroughs, and government policy of closing schools with surplus places.
There are 110 grant-maintained schools in London, and most have taken charge of their own admissions.
'This year is worse than ever,' said George Varnava, representative of the National Association of Head Teachers and head at Norwood School in Lambeth. 'Parents are making multiple applications within their own boroughs, in other boroughs and between council controlled and grant maintained schools .
'In many cases there is no communication between the grant-maintained schools and the education authority. There is no way of telling what people's first preferences are or where they are going to go. Heads have to plan lessons when they don't know how many classes of 11-year-olds they will have in September.
'Our system fragmented after the abolition of the Inner London Education Authority. Now not only do we have to cope with grant-maintained schools doing their own thing, but with 32 different boroughs.
'We have children where we do not know where they have gone,' said Richard Martini, head of policy and planning at Lambeth Council. 'It is particularly hard when we are trying to find non-attenders. We have to check names, call schools to see if they are on the roll. Some children, whose parents are not bothered about them going to school, can slip through the net and it takes us longer to find them.'
Researchers from Agency 26, an educational think tank, say the government exam league tables do not give a true picture of a school's performance. In Lambeth 50 per cent of children are educated outside the borough. 'People think the grass is greener, and sometimes a school may have excellent PR rather than the best exam results,' said Mr Varnava.
One school, Dick Shepherd, is under threat of closure because of poor exam results and surplus places. This year only four 11-year-olds named it as their first preference. The fact that the number of pupils gaining five GCSE passes increased by 25 per cent last year, or that Agency 26 doubted if 'any school could possibly get better results with such disadvantaged pupils', will not help it.
At the other end of the spectrum some schools are so oversubscribed that some local children can no longer get places.
In Kingston, councillors are investigating opting out of the High Court ruling and limiting intakes from other boroughs.
Bill Dickinson, director of education, said: 'Kingston is long and narrow, which means parents from over the border often live closer to some popular schools than those in the middle.
Enfield and Hillingdon have devised co-ordinated admissions systems to reduce uncertainty.
Rod Stafford, chairman of the Hillingdon Association of Secondary Head Teachers, said: 'There is now a balance between the supply of places and the number of students transferring to secondary schools, but because of the location of the closing schools, children in some areas cannot go to any school near their homes. For those parents there is no choice.'
The Department of Education said: 'While the Government believes voluntary arrangements are best, it reserves the right to direct grant-maintained schools and local authorities to adopt a co-ordinated policy. The Secretary of State deplores the use of false names and addresses by parents to gain access to schools. Such actions are wholly unfair.'
Additional reporting: Mark Kilfoyle
'WHY AREN'T WE ALLOWED TO GO TO OUR LOCAL SECONDARY?
When Lauren Davies, 11, leaves junior school this summer, she wants to go to Fortismere, the most popular school in Haringey, north London.
It is not an unreasonable ambition. Other children in her street - which is in the catchment area - attend there and so do many former pupils of her present school, Campsbourne.
Last year Lauren would probably have been accepted. This year she has no chance; the Muswell Hill school is oversubscribed, with 407 children vying for 216 places. Instead she has been offered a choice of three schools on the other side of the borough.
More than 30 parents are in the same predicament with their children. They are angry and want to know where the surplus applications have come from. They believe the council did not anticipate the demand.
The authority offers a simple explanation. Fortismere came within the top 100 state schools in the Government exam league tables. Good GCSE results attracted more applicants from inside and outside the borough.
Haringey has no grant-maintained schools but there are plenty in neighbouring boroughs. So the figure may be boosted by parents making multiple applications to grant-maintained schools outside the authority's control. Richard Jones, director of education at Haringey, said: 'Our staff are checking the electoral register. We have no evidence of people lying, but the protesters insist it has happened.'
The parents are now thinking about teaching their children themselves. 'We chose Fortismere because it is close, has a good library and a range of extra-curriculum activities,' said Julia Davies, Lauren's mother. 'There is no way our children are going to take a three-mile bus journey across the borough.'
THE MOST POPULAR GRANT-MAINTAINED SCHOOLS
Each school has at least three applications for every place:
Queen Elizabeth's, Barnet.
St. Michael's Catholic Grammar, Finchley.
Beaverwood for Girls and Bullers Wood for Girls, Chislehurst.
Hayes School, Hayes.
Coopers School, Bromley,
Langley Park Boys, Beckenham
Newstead Wood School for Girls, Orpington.
St Olave's and St Saviour's Grammar School, Orpington.
The Ellen Wilkinson School for Girls, Acton.
Latymer School, Edmonton
The Coopers' Company and Coborn, Upminster.
Bishopshalt School, Uxbridge.
Tiffin School for Boys, kingston.
London Nautical, Southwark.
Nonsuch Girls High, Cheam.
Sutton Boys Grammar, Sutton.
Wallington High for Boys.
Wallington High for Girls, Wallington.
Wilson's School, Sutton.
THE MOST POPULAR COUNCIL-RUN SCHOOLS
Barking and Dagenham: Barking Abbey, Barking
Barnet: Copthall School, Mill Hill
Bexley: Blackfen School for Girls, Sidcup
Camden: Camden School for Girls, Camden
Greenwich: Thomas Tallis School, Blackheath
Hackney: Kingsland School, Shacklewell
Hammersmith and Fulham: Lady Margaret School,
Parsons Green (voluntary aided)
Fulham Cross Girls School, Fulham
Haringey: Fortismere School, Muswell Hill
Hillingdon: Bishop Ramsey Church of England
School, Ruislip (voluntary aided)
Hounslow: The Green School for Girls, Isleworth.
Islington: Highbury Fields Girls, Highbury.
Islington Green School, Islington
Kensington and Chelsea; Sion Manning RC
Kingston-upon-Thames; Tiffin Girls (selective), Kingston. Coombe Girls School, New Malden
Lambeth; Every LEA school is undersubscribed
Merton: Rutlish High School for Boys,
Wimbledon, Chase (voluntary aided)
Richmond upon Thames: Grey Court School, Ham
Tower Hamlets: Swanlea School, Bethnal Green
Waltham Forest: Rush Croft School, Higams Park
Wandsworth: Chestnut Grove School, Balham
Westminster: Grey Coat Hospital, Victoria
No information available: Bromley, Croydon,
Ealing, Enfield, Harrow, Havering, Lewisham,
Newham, Southwark, Sutton
No state schools: City of London
WOULD YOU GO THIS FAR?
1 Move house, preferably next door to the school.
2 Give a false address. This will not succeed if education officers check the electoral register.
3 Insist your 17-year-old son takes A levels in the sixth form, then claim your 11-year-old must attend.
4 Rent a second home in the borough of your choice.
5 Divorce your partner and marry somebody with children at the school. Step-children count as siblings too.