Cambridge was separated from second-placed Oxford by a fraction of a point out of 1,000 when The Times published Britain's first university league table 15 years ago. Since then the way that the ranking is compiled has changed with the higher education system, but the two old rivals have continued to vie for top place.

Indeed, Imperial College London can be added to the perennial table-toppers. Never out of the top three, Imperial even overtook Oxford in the 1999 guide.

The changes have come farther down the table. Bristol, Edinburgh and Bath have been in the top five and outside the top ten; Exeter, Surrey and Sussex have been in the top 20 and well outside the top 30. Six different universities have been bottom.

Professor Tom Cannon, a former director of Manchester Business School, who compiled the first table, believes that universities such as Warwick, York and Bath have been the main beneficiaries.

He says: “The rankings have vindicated the achievements of the newer universities, especially those from the 1960s, above those who relied on their historic position. I'm more convinced than ever of the value of the tables. They have delivered a service, particularly to students with no background in higher education, and they have helped to improve standards in higher education.”

Universities might not agree. They certainly did not when the first table appeared. The Committee of Vice-Chancellors and Principals, the forerunner of Universities UK, said: “We believe the tables are wrong in principle, flawed in execution and constructed upon data which are not uniform, are ill-defined, and in places demonstrably false.”

The new universities, the establishment of which was the reason for producing a guide, were particularly critical. This was understandable since all of them appeared below all the old universities in that first table.

Gradually this began to change. In 2001 Oxford Brookes was in the top half of the table, above City University, Brunel, Heriot-Watt and Keele. Northumbria was above Ulster and Bradford. The results of the

2001 Research Assessment Exercise helped some of the old universities to reclaim their previous positions, although there was no change in the weightings used in the table. But even last year, Oxford Brookes finished above Dundee, Brunel and Goldsmiths, University of London.

However, this year's table shows the most marked divide between new and old universities since the early years of the guide, with only Lampeter and Salford finishing below any of the former polytechnics. The shift cannot be blamed on research scores, since they have not changed for six years and there are no new measures or weightings. Measurements have changed over the years, however.

Perhaps the biggest change has been in the number of universities, which has grown from 96 in the first table to 113 this year, even though five of the original complement have disappeared through mergers or a lack of data.

Times recommends

• Students face big rise in university fees
• Students to rate lecturers online
• Lord heads team to look at raising tuition fees