AS THE head of a large and successful sixth form college, Godfrey Glyn should have every reason to feel satisfied. Barton Peveril college, at Eastleigh, Hampshire, is still basking in the glow of an inspection last April that judged it outstanding on achievement and standards.

However, Hampshire’s system of post-16 colleges - a well-regarded feature of the county’s life for more than 30 years - may be under threat. Mr Glyn told MPs last month that local secondaries, which have traditionally been 11to 16 only, are being encouraged by advisers from the Specialist Schools and Academies Trust to set up sixth forms.

He fears that, if implemented, the change will throw his college and others in the county into instability, as schools are encouraged to fight it out with colleges for market share.

This concern is echoed at several of England’s other 100 sixth form colleges, many of which have been the first choice for A-level pupils for decades.

The Government wants successful 11 to 16 schools to develop sixth forms.

Last year’s Education Act enshrined in law a “presumption” that successful specialist secondaries would be allowed to introduce post-16 provision.

In addition, The TES has been told that the academies division of the Department for Education and Skills wants academies to be set up with sixth forms.

In all, the Government believes, 60 new school sixth forms will be created over the coming years. This, it says, will cater for increased demand from students, as ministers aim to increase participation rates. At the same time, up to 50 colleges will also be allowed to expand.

But is this a welcome response to parental demand?

College leaders claim not. They say it is, instead, a recipe for uncertainty and inefficiency that could add to tax bills while lowering standards, There is no guarantee, they add, that post-16 school and college numbers will rise, as the number of 16 to 19-year-olds will start falling from 2009.

The Government may now be looking to make it compulsory for all 16 to 18-year-olds to be in education or training, but the colleges believe much of this will be work-based. Schools and colleges will be expected to compete, at the very time when the Government says they should be working together to offer the new specialised vocational diplomas, which will be launched next year. Colleges argue that they do a better job with their students than school sixth forms and spend taxpayers’ money more efficiently, offering students a broader range of courses.

If all this sounds like special pleading, a string of recent reports appear to add weight to the colleges’ case. A Learning and Skills Development Agency study, which analysed college accounts, found that institutions with less than 200 A-level students required “substantial subsidy” to break even. Those with between 200 and 500 students could offer more financially “efficient” provision, but only at the cost of restricting the range of courses they offered.

Those with more than 1,000 could offer multiple courses at a much cheaper price because of economies of scale.

But is this just a pile-them-high-price-them-cheap philosophy? Do the more intimate surroundings of small sixth forms, particularly in schools, where many youngsters will have studied since the age of 11, yield better exam results?

Again, two recent reports suggest not. Another report by the agency, funded by the Government, compared GCSE results of nearly 50,000 students in 2001 with their A-level grades two years later. It found that sixth form college students had better A-levels, given their GCSE grades, than those in either school sixth forms or FE colleges.

A separate study of more than 90,000 students in 2005 by Alchemygold, a data analysis company which examines post-16 “value-added” information, had similar findings. Again, the colleges emerged as slight winners, at all levels of ability, with little difference between the grammars and the comprehensives.

Colleges, then, feel justified in arguing against moves to increase the number of school sixth forms.

Nick Brown is principal of Oldham sixth form college, which is a beacon institution. His local auhtority has published plans to replace five secondaries with two academies.

It is not stated whether or not they will contain sixth forms. But Mr Brown is concerned the plan could destabilise an arrangement which, he said, was universally valued in the town.

Others do not share the colleges’ view, however. Philip May, head of Costessey high, outside Norwich, said local staying-on rates had risen “massively” since his school introduced a sixth form in 1995.

“Sixth form colleges do a good job,” he said. “But they are large institutions. Some students want to stay in places that they know, with teachers they know, and where they do not need to travel far. If schools want to expand, they are only going to do that for one reason - parents and students want more choice.”

Much will hinge on whether the Government’s drive to raise post-16 staying-on rates translates to more school and college learners. If the numbers do rise, expect heat to be taken out of this debate.

If not, there is potential for some bitter turf wars between schools and colleges.

The numbers game: 16 to 18-year-olds

Secondary schools 362,800 full-time (or equivalent) sixth formers in 11-18 schools with sixth forms.

Sixth form colleges 140,500 students.

FE and other tertiary colleges 442,500 students.

Higher education 146,400 students.