For the outside world the universities of Oxford and Cambridge are their colleges. The glorious medieval architecture of King's, Trinity, Christ Church, and Magdalen mark "Oxbridge" out from all other universities.

But behind these elegant stone facades the true picture is a complex one - a subtle balance between the power of the colleges and that of the central universities of which they are part.

This year in the FT's UK Universities Survey the colleges publish - for the first time - data on their contribution to the education of their students.

Generally, colleges select and admit students, provide rooms and facilities, and give tutorials. The universities determine the courses, organise lectures and seminars, provide communal resources, such as laboratories, set exams and award degrees.

League tables in the past have failed completely to show how colleges contribute to providing books, IT, and - most important of all - academic staff to run the powerhouse of the college network, the tutorial system.

They have also failed to take account of the extra income which flows into colleges from research grants and from industry.

This year's FT snapshot - for 1998-99 - is part of a moving picture. This is a financial system in the throes of great change. The Labour government has abolished the special "college fees" once paid direct to the colleges to help meet the costs of the tutorial system.

Over ten years this support - now paid direct to the universities centrally - will be removed at a rate of 10 percentage points a year.

But other funds, now open to all universities, will particularly help Oxbridge. First, there will be extra cash for the upkeep of historic buildings and, second, additional support for teaching in small groups.

The figures published today in full for the first time cover the last year of the old "college fee" system. So, the money which supports the investments shown have come from two sources - public funds and college endowments.

In future, colleges will have to rely more on their own funds and the richer colleges will have to help support the system in the poorer colleges.

One thing is certain in this uncertain future - the determination in both Oxford and Cambridge to continue to fund the collegiate system.

Dr Robin Walker, Junior Bursar at Queens' College, Cambridge, believes publishing the figures will reveal the extent to which the university's past performance has been under-rated.

"League tables have understated the position at

Cambridge [because they have omitted college spending]. These funds have a positive effect - a beneficial effect - on the student experience," he says.

"There are three ways in which this benefit can be felt: there is college-based teaching from the fellows; college libraries with text books and reference books; and there is IT."

He takes the example of a first year undergraduate in natural sciences at Queens' who would expect to spend 12 hours a week in lectures and an additional 4 hours a week in tutorials - with additional time spent in the laboratory.

"This is not, therefore, a marginal consideration; it is quite central to the student experience at Cambridge."

He insists that such tutorials - often either face to face or in very small groups - contribute to the quality of the work produced at Cam bridge.

Queens' also has 45 teaching fellows - 10 are full-time employees of the college. Many are Junior Research Fellows. "This is about sowing the seed of future academic careers - we keep them warm, so to speak, at the start of their careers."

There are also College Teaching Officers who help fill gaps which appear in some subjects. There is also another huge benefit to students at Cambridge college rooms and facilities. "There is no need ever at Cambridge for the undergraduate to go into the private [rented accomodation] market," says Dr Walker.

Prof Averil Cameron, Warden of Keble College, Oxford, believes college spending on books and IT is vital to underpin the "rigorous regime" that students are expected to follow.

She sees the tutorial system as a way of regulating this regime - checking that students are up to speed, that they are producing the essays they should to the required quality. The system, which requires essays to follow individual research and then to be tested through argument and discussion, relies on having to hand the facilities for individual research, she says.

At the beginning of each term, for example, returning students face at least one three-hour paper - and possibly two covering the previous term's work and new study set for the vacation. Students face interviews - "collections" - at least once a year and in the run-up to public exams if they are falling behind.

"This is a system which teaches them to think independently. I think it makes them employable as well -because they have been through this rigorous discipline."

Prof Cameron went to Somerville, Oxford. "I think it gave me the capacity to build an argument. To set out the reasons why I felt I was right and defend my opinion." The tutorial system underpins such skills.

Keble can offer its 430 undergraduates 24-hour access to its library and all the 370 rooms have been linked up to the internet. Prof Cameron, who is chair of the Conference of Colleges, says: "The university could simply not supply what the colleges supply."

The data released today also highlight the research income which flows into the colleges - separate from that which goes to the university. "There's a lot of hidden help for research from the colleges."

Colleges are not just about teaching. "We want all our staff to be active in research," says Prof Cameron. Colleges also have a vital role in providing cross-fertilisation between academics and students in different disciplines. This is seen as a vital role as the 19th century demarcations between subjects break down and the new economy flourishes in many of the "grey areas" between traditional disciplines.

"We meet each other in the dining hall - in common rooms. There's a lot of contact," says Prof Cameron. Colleges, although small by the standards of most universities, normally strive for a broad spectrum of disciplines in order to maximise such benefits. This is a model many universities are trying to follow without the benefits of the small-scale college system.