Let us look at some raw scores in 1994, in Table 1 below: Can we conclude that Manchester Grammar is best, Bradford Grammar is next and Greenhead College is third? Not necessarily, I would suggest. The key question not answered is, what had these students gained at GCSE before they started their A-level studies? From what base have they started?

In the case of both Manchester Grammar and Bradford Grammar, the average student at GCSE gained five grades of A and four grades of B, not unexpected given the high degree of selection at 11-plus. In the case of Greenhead College, the average student achieved one grade A, six grades of B and one grade of C prior to undertaking A-levels, much lower than for the other two schools. The intriguing question is, if students at the grammar schools had come to this sixth-form college, would they have done as well?

Say Greenhead College had been as selective as the two grammar schools and had taken students only so as to give an average GCSE base of five grades of A and four grades of B. We would have refused entry to 242 students and selected only 107 students from the 349 who sat A-levels in 1994. As a matter of record, the discarded 242 students sat 700 A-level examinations, passing 88 per cent of them with almost a quarter at grades A or B.

Now let us look at the selective group of 107 students. They achieved a pass rate of 99.5 per cent with grades of A and B achieved in more than 71 per cent of the entries. The average UCAS score per student was 29.7, while the UCAS score per subject taken was 7.9. So we can now produce Table 2.

However, even this gives a slightly false picture. Greenhead College students gain the highest UCAS points per student because they do marginally more A-levels per student than the other two. However, what the analysis really shows is that there is no material difference in performance between students of like ability in the three institutions. Yet in the recent Financial Times top 1,000 schools listings, Manchester Grammar is 11th, Bradford Grammar is 64th and Greenhead College 482nd, highly misleading to the public.

So what conclusions can we draw from this? First, league tables are only valid if you compare “apples with apples”.

Second, the best of the state sector equals the best of the selective independent sector, and similarly the worst of the independent sector do equally excellent work with students of lesser ability, as do selective schools with their “creamed” intake. And finally, and ironically, colleges such as Greenhead College achieve these results at a cost of around Pounds 2,500, while similar education in private selective schools costs anything between Pounds 4,000 and Pounds 9,000, sometimes paid by the taxpayer through the Assisted Places Scheme. So where good state schools and colleges exist, this is where one finds best value for money.

So when the top 100 is published, have a look at the top 10. I believe that if their pass rate is less than 99 per cent, or their AB grades are less then 71 per cent, they do not match Greenhead College and many other state colleges and schools.

Kevin Conway is principal of Greenhead College in Huddersfield.