PARENTS who pay thousands of pounds in private school fees may not be buying their children a better education, a TES analysis reveals.

Only about 75 per cent of schools inspected by the Independent Schools Inspectorate last year were graded “good” or better compared with 68 per cent of state secondaries and 65 per cent of state primaries.

Parents pay fees of pound;8,000 a year for day schools on average, although exclusive boarding schools charge up to pound;18,000, according to the Independent Schools Council. But their chance of getting a “good” school is only about 10 per cent better, than those who opt for the state sector, where funding averages pound;3,380 per pupil, excluding London.

The findings come a week after the council revealed that private school pupil numbers have risen by more than 8,000 in a year, to a total of more than 500,000. There was also a rise in the number of boarding school pupils for the first time since 1987.

The TES analysed 161 private schools inspected in 2001 whose reports had been posted on the inspectorate’s website by late April.

One private-school head, who has worked as an inspector for the Office for Standards in Education and ISI, said fee-paying schools underestimated the high quality of teaching in their state competitors.

She said a number of prestigious independent schools she had inspected were “coasting on their reputations”, and that some staff at the most selective were getting away with unsatisfactory teaching because their pupils were so motivated.

The average pupilteacher ratio in private schools is 10.4, compared with 18 in the state sector. At GCSE, last year, 94 per cent of pupils achieved A* to C in the private sector compared to 57.1 per cent.

Margaret Tulloch, of the Campaign for State Education, said: “People should not assume that if they are paying they are going to always get something better.”

But Bob Carstairs, assistant general secretary of the Secondary Heads’

Association, said: “You will always get parents who are prepared to pay up to pound;16,000 a year because they see that as their children’s birthright.”

Dick Davison of the ISC said parents used criteria other than inspection reports to judge private schools. “Parents say they are looking for small classes, high standards and discipline,” he said.

He added that the inspection regimes were different with independent schools being subject to “a kind of peer review”.

Tony Hubbard, director of the ISI, said it was “not clear” whether the two sets of inspections could be compared. “Our criteria are not identical,” he said. “OFSTED uses a very detailed judgment-recording form, while we give a general grade.” A private school would be described as good if it, for example, achieved high standards in relation to ability and offered good teaching.

Mrs Tulloch said: “You could argue that what parents could ask for is an inspectorate inspecting across the board so that they know they are comparing like with like.”

ISI inspectors are not obliged to grade schools as good or very good but many do.