Nearly 40,000 more children are now being educated privately than when Tony Blair came to power, new figures reveal today.

Despite increasing government spending by two thirds, in real terms, since 1997, record numbers of parents are turning their backs on state education and paying up to £25,000 a year for private education.

Average private day-school fees have more than doubled in this period, according to a report from the Independent Schools Council.

Almost a quarter of sixth-formers now attend a private school while, in London, one in seven pupils is privately educated; in Edinburgh it is one in four.

Overall 509,093 children attend Independent Schools Council (ISC) member schools, where the average pupil:staff ratio is the lowest ever, and there is one teacher for every 9.7 pupils. This compares with a ratio of 17:1 pupils to staff in state schools.

Despite average fees of £8,790 and a drop in the number of British children of school age, there has been no let-up in the number of parents opting for private education. Head teachers say that this is not only because society is getting richer and families are having fewer children, but because parents are also better informed and more concerned about education.

Pat Langham, president of the Girls’ Schools Association, said: “A lot of parents cannot find a school that matches their requirements in the state system. That awareness is what is making more people prepared to pay for independent education. They know what they are getting and they know it’s good.”

Mounting pressures of commuting and long working hours have also persuaded more parents to turn to independent schools to give their children the care and attention they cannot always provide at home.

At the same time, low teacher turnover provides stability and smaller class sizes mean pupils receive more attention and are better disciplined, Nigel Richardson, chairman of the Headmasters’ and Headmistresses’ Conference of elite schools, said.

“A lot of parents are both working very long hours and they increasingly value knowing that they will meet the same teachers three or four years running who will know their children.”

Jonathan Shepherd, general secretary of the ISC, said that public schools had also bucked the demographic trend because they offered a broader education and wider range of subjects, including modern languages, classics and the sciences at A level.

“The Government did make one quite major mistake in making languages optional after Key Stage 3,” he added. “That has led to a huge decline in language teaching in the maintained sector. Parents talk to parents. They are the best recruiting agents for any school.”

In 2004, the Government made languages optional for pupils over 14. As a result, only 51 per cent of teenagers now take a GCSE in a foreign language, compared with 80 per cent in 2000.

Languages are now compulsory in only 17 per cent of state schools at this level. Critics suggest that schools are being motivated by their place in the league tables and tend to guide pupils away from studying languages towards easier subjects.

As a result, independent school pupils account for more than half the A grades at A level in French, German, Spanish and other foreign languages. In chemistry, they make up 46 per cent of A grades at A level, 44 per cent in physics and 54 per cent of A level further maths A grades.

The Independent Schools Council covers 1,276 schools from nursery to sixth-form level, including Britain’s most elite, of a total of 2,500 independent schools.

Fourteen schools now charge more than £25,000 a year and the average boarding school fee at secondary level is £20,000. Of the half a million pupils, just 67,335 are boarders.

The annual census also reveals that 20,852 overseas pupils attend public school in Britain, the majority from Hong Kong and China. Although the number of boarders has dropped slightly, Britain’s military commitments in Afghanistan and Iraq may account for a surge in the number of Armed Forces families sending children to private schools.

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