The analysis by the Association of Colleges has dampened what little enthusiasm there was in the sector for the latest White Paper, Learning to Compete, which aims to set out an agenda for education and training for all 14- to 19-year-olds for the 21st century.
College principals were angry at a U-turn in the White Paper by Gillian Shephard, the Education and Employment Secretary, following an earlier pledge to act on calls to eliminate unfair differences in college and school spending.
Mrs Shephard began her rethink earlier this year when an internal department paper suggested the claims were exaggerated. Civil servants argued that for a three A-level student, sixth-form colleges were 7 per cent better off than schools or colleges but that there was little difference between the latter.
Colleges challenged this and ministers promised that if discrepancies did emerge on closer analysis, they would make amends. But the 14-19 White Paper was published before any new evidence had been looked at.
A further funding document will be out in the spring - too late to change policy.
John Brennan, policy director for the AOC, pressed government advisers to explain their findings and analysis. They finally conceded that colleges could be 5 per cent worse off than schools.
"They said it was not statistically significant. But when I asked them to explain, they were unable to say how they arrived at the margin of error, " he told The TES.
"Even on their own figures, calculated properly and in the most favourable light to them, the colleges come out 5 per cent worse off. That would be Pounds 150 per student, and that is not peanuts. However, I calculate the figure to be Pounds 300."
Roger Ward, the AOC's chief executive, said: "This White Paper is the best of intentions and worst of funding proposals. Colleges are not getting their fair share."
Colleges are also deeply sceptical of the proposals in the White Paper for learning credits, and they see little advantage in extending them to cover young people up to 21.
At the launch of the White Paper, Mrs Shephard said the credits would carry a guarantee of an individual's entitlement to education and training at school, college or in the workplace. It would not carry a cash value, she said.
"This scheme does not move us any closer to vouchers," she added.
Mr Brennan said: "It is unclear what value credits will add to existing entitlements, and if they simply become a bureaucratic paper chase, then they will hinder rather than enhance the responsiveness."
College heads gave a cautious welcome to many aspects of the White Paper but few of the principals who spoke to The TES saw any significant proposals in it.
The planned vocational options post-14 and the proposed national traineeships were from the Dearing review, they said. And the recognition of the need to prevent pupils dropping out was simply a rubber-stamping of successful local initiatives that had nothing to do with government policy.
The convergence of funding arrangements, with school sixth-forms being subject to the system of payment by results in colleges, was seen by the AOC as "a move in the right direction".
Colleges welcomed Mrs Shephard's pledge to fund "innovative local partnerships" to motivate young people who might otherwise drop out of education.