Private school students on the Assisted Places Scheme cost up to three times as much as those in sixth-form colleges without any significant gain in standards, research suggests.
Studies by the Sixth Form Colleges' Association and Birmingham University indicate that sixth-form colleges are the most cost-effective way of providing post-16 studies.
The association started its own research after ministers insisted there was inadequate information for reliable comparisons. Initial findings were debated at the summer conference of the association in Oxford this week.
The average cost of a place in an LEA school sixth form is Pounds 3,106. At a city technology college it is Pounds 3,550 and under the Assisted Places Scheme it is Pounds 4,728. Some places covered by the scheme cost around Pounds 8,000, while the average cost of a sixth-form college student is Pounds 2,734.
The figures emerge from a study of official statistics from the Audit Commission and the Further Education Funding Council and others from a series of parliamentary questions by the association.
Other studies show that since incorporation, colleges have lost hundreds of staff or had to take on many more students with little extra cash. Pressures to cut unit costs have hit them harder than either the schools or general further education colleges.
Many have around 15 per cent fewer staff than they would if they were still under LEA control, or else they have seen an equivalent rise in student numbers as staff-student ratios deteriorate.
Typically, the 1,250-student John Ruskin College in Croydon has 200 more students and 89 staff, 12 of whom are part-timers, giving a ratio of around 12 to one. Under the LEA ratios it would have 102 full-time staff. John Deane College in Cheshire is similarly affected, with an SSR of 1:15 compared with the LEA's 1:13.5.
The colleges concede that they have seen substantial improvements in capital funding for buildings and have more control over the curriculum. But salaries have dropped as incentive allowances available under the schools sector have been virtually abolished in an effort to cut costs.
Four years ago, Professor Hywel Thomas of Birmingham University carried out detailed research which showed that sixth-form colleges were the most cost effective organisation, giving the best student support services, offering a broad curriculum and getting the best results.
The Sixth Form Colleges' Association has commissioned him to update that research and draw in wider evidence on relative funding levels. A briefing paper will be produced over the summer aimed at putting pressure on MPs in the run-up to the next general election.
Geoff Mason, a member of the FEFC tariff committee and deputy principal of Esher SFC, initiated the research.
He insisted that the association was not about to plead for special treatment.
"We are convinced that there are arguments for a fairer funding formula, " he said.