They are angry that schools where students stay on after 16 to follow vocational courses will appear in a bad light to parents because of the way the tables are being drawn up by the Department for Education.
These students will appear only as 'not entered for A-level or A/S- level' in the lists of schools' examination results due to be published next month.
The omission effectively undermined ministers' stated aim of promoting vocational qualifications in schools and giving them equal status with academic courses, the Secondary Heads' Association said.
Lawrence Montagu, head teacher of St Peter's Roman Catholic High School in Gloucester, said that parents would get the false impression that 19 per cent of the age group had not even been entered for A-level after two years' work. 'The public are going to ask what the school has been doing,' he said.
In fact, that figure represented 14 students who successfully completed a vocational diploma, Mr Montagu added. Eight of them had gone on to higher education.
Yesterday, the Department for Education said that it was ministers' firm intention to include vocational qualifications such as Btec or City and Guilds next year, but it had not been possible to do so in the first year. It would be open to any school to include details of such courses in its brochure. 'The problem we had was the difficulty of collating these figures. We are certainly not decrying the value of vocational qualifications,' it added.
Mr Montagu said: 'It doesn't help us in the eyes of the public this year. We tell the students on vocational courses that they should not feel second-class citizens, yet here they are publishing results that do not take any account of the excellent work they have done. Parents will look at the tables and gain an impression that is very wrong. The schools that are going to be punished are the ones that are more advanced in terms of what the Government wants.'
John Sutton, general secretary of the association, said: 'All our members are quite disgusted about the publication system. There are a lot of anomalies, but this is one of the most horrendous. It disregards the achievements of schools and also of the young people themselves.'
This year's GCSE and A-level results for all schools in England and Wales will be published in free booklets for each local education authority and in local and national newspapers.
For each school, the numbers of 15 and 17-year-old pupils will be given. Alongside will be the percentage of the age group entered for at least one A or A/S-level examination and the average points score per candidate.
For GCSE, four columns will display the percentage in the age group obtaining five or more A to C grades (approximating to the old O-level); five or more grades A to G; one or more grades A to C; and one or more grades A to G.Reuse content