John Harwood, chief executive of the council, has told education officers that harmonising local provision could take up to six years.

In a special report on the Learning and Skills Act, The TES reveals that around two-thirds of sixth forms have fewer than 200 students - the magic number seen as financially and educationally viable.

But schools and authorities are already coming up with their own reorganisation plans.

Sweeping changes for post-16 education in Greenwich, south-east London, have been agreed by its school organisation committee. Four sixth forms are to be replaced by a network of five, new, independent “centres for advanced learning and skills”.

Meanwhile, there are fears in North Yorkshire that school sixth forms could be threatened when the skills councl takes over their funding.

County councillor John Dennis has written to Mr Harwood, ministers, Conservative leader William Hague, and heads and governors of 48 schools.

“People assume that if courses are not available at one school, they can just go somewhere else. But that is physically and geographically impossible,” said Mr Dennis.

North Yorkshire’s average school spending is above average and councillors fear that the LSC will use a national formula for funding which will not take account of the extra costs incurred in rural aras. “There is London weighting but no rural weighting,” said Mr Dennis.

Reorganisations are being driven both by education authorities and by the Office for Standards in Education. OFSTED aims to inspect one-third of the country by the end of 2002. It is likely that the result of many of these area inspections will be to argue for a reduction in school sixth forms.

LSC special report, pull-out