The drive for more sixth-form colleges has become something of a cult. Ever since Tony Blair's adviser, Andrew Adonis, expressed a desire to see one in every town their merits have gone unquestioned.
Efficient, offering high standards, they were as appealing to middle England as the cherished school sixth forms. They also offered New Labour a politically expedient option: if small, unviable sixth forms must go, these "super-sixths" could replace them.
Margaret Hodge, then the further education minister, firmly believed in segregated 16 to 19 provision. Heeding the political signals, general FE colleges created age-segregated sixth-form centres within their walls.
But what if they have got it wrong? There was no firm evidence either way - until now. Professor Stephen McNair's unique research (page 1 and right) challenges assumptions about teaching discrete age groups. While it points to some benefits, the overwhelming message is anti-segregation.
The merits of teaching 17-year-olds alongside the over-50s have been known anecdotally for years and, it seems, the Department for Education and Skills is coming round to this view. As Professor McNair's research went deeper, considerable evidence for the educational value of mixed-age learning emerged from the banks of inspection data.
But will the message get through to the local learning and skills councils as they carry-out strategic reviews of all post-16 education and training in their area? They are under tremendous pressure to rationalise, cut costs and close unviable institutions. And with the clear message that there is little new money on the way, there is a danger that cash-cutting imperatives will come first.
If anything is part of Mr Blair's Big Conversation, this is. Questions of reorganisation cannot be rushed, they are as central to post-school learning as the current Tomlinson debate over the future of A-levels. That debate, remember, is running until 2010.
More research must be done on the relative merits of mixed and segregated learning. As colleges contemplate plans to increase 14 to 19 provision, they cannot afford to get wrong the pressing questions of pastoral and other support. The LSC must implement radical reforms spelled out in the strategy document Success for All by 2005. The question of how colleges organise their classrooms, workshops and learning centres, to suit all ages, will take much longer.