Sixth-form colleges left local authority control to become free-standing corporations after being included in the 1992 Further and Higher Education Act virtually as an afterthought.
Incorporation was broadly welcomed by many principals as a chance to take control of the destiny of their colleges and deploy resources as they wished.
One consequence has been that colleges have diversified the range of courses they offer from GCSEs and A-levels to include GNVQs, NVQs, adult part-time education and community work.
In this sense many have come to resemble medium-sized FE colleges and a few are even a little tertiary-like.
A minority of more traditional sixth-form colleges have continued to concentrate on academic qualifications. Some, especially in well-heeled middle-class areas in the South such as Cambridge and Hove, are flourishing. Others seem to be struggling.
However, all sixth-form colleges are now complaining that the pips are beginning to squeak after years of having their funding squeezed.
The move towards an average level of funding has led to widespread teacher redundancies, re-structuring, increased contact hours, larger classes and heavier workloads.
Colleges have grown dramatically as their work has diversified and as a result of the demand-led element - cash set aside for growth which has now been abolished.
Smaller colleges are being taken over by larger colleges. The financial future of a significant number of colleges is uncertain and job insecurity is rife.
Many teaching staff are demoralised and stress levels are high. The overall culture of a permanent, full-time and part-time lecturing staff has, on the whole, survived without great recourse to hiring part-time casualised teachers from outside agencies.
However, there is mounting concern in the sector about the uneven funding between colleges and school sixth-forms. On the whole local authority sixth-forms are better funded.
There is also concern among principals that, because they have to fund teachers' pay increases from their own resources, they are unable to match school salaries. There are signs that colleges are beginning to have difficulties recruiting.
Nick Brown, principal of Oldham Sixth Form College, said: "Teachers in sixth-form colleges work incredibly hard and each year are expected to do more, yet they have seen an erosion of their salaries. It will lead to recruitment difficulties, quite apart from the fact that I do not think it is right."
While a national pay and conditions agreement exists between the unions and employers in the sector, individual colleges are finding it increasingly difficult to honour national pay awards.
Despite moving out of local authority control, links with feeder schools and local authorities are still generally good, although such relations are more tense in areas where schools have sixth-forms. Some colleges still buy services from local authorities.
The funding pressures have fuelled the debate about whether colleges should have ever left local authority control and whether it is now time to return to the fold of local schools.
There is also a growing realisation that the Government's New Deal, widening participation and lifelong learning agenda may not offer very much for traditional sixth-form colleges.
Peter Daley, principal of Pendleton College in Salford, said: "Some sixth-form colleges believe that it was a mistake to take them out of local authorities. They believe that they are not equipped as small caring organisations to compete in the cut-throat world of competition and efficiency gains.
Others, he says, are flourishing and never want to go back into local authority control.
David Igoe, principal of Cadbury Sixth Form College in Birmingham, says that the benefits of incorporation include being in control of your own destiny.
There is something of an identity crisis in some of the more traditional colleges. Principals are wondering whether they fit into the FE sector or would be better off elsewhere.
"It's very hard for us to see a future within the FE agenda, unless you have diversified," Mr Igoe said. "Those that have feel much more comfortable in the new world of FE."
The traditional colleges will not, as a general rule, benefit from any extra money for enrolling more students for lifelong learning because the colleges do not usually draw their students from deprived areas. "That has really sharpened the debate about the future," Mr Igoe says. "What a tragedy if sixth-form colleges go under, and they may well do, because they may not be able to sustain the pressures."
"The signs are there that many of us may go over. That would be a tragedy because the jewel in the crown will have been thrown away for no good reason," he said.
Jack Tasker, principal of Sir John Deane's College in Cheshire, said that fairly traditional sixth-form colleges which believe in one-to-one attention, team sports and pastoral care, have more in common with secondary sixth forms than large FE and tertiary colleges. "It's not just about examinations, it's about preparation for higher education, employment and so on," he added.
More important, he said, was the notion of looking at the nation's 16-19 provision, separate from adult education and lifelong learning. He said regional planning boards and a national strategy for 16-19 education in schools, FE colleges and sixth-form colleges was needed.