GOVERNMENT spending on schools needs to rise from pound;25 billion to around pound;42bn to meet the Prime Minister’s target of raising state-school budgets to private-sector levels, it was claimed this week.

While welcoming the aim, the Independent Schools Council is doubtful if such spending could be achieved without steep tax rises - unless the arrangements for financing education were changed.

A survey published yesterday suggests that, if the Government is to entice parents of children at private schools back to the state sector, it will have to find a way to cut class sizes.

Smaller classes are the biggest single reason parents go private, according to a MORI survey conducted for the Independent Schools Council. However, they are also the main reason for the higher spending per pupil in the independent sector.

The survey found that more than one in three (36 per cent) parents of children recently admitted to independent schools cited class size as their main reason for going private. Among prep school parents, the proportion was almost half (46 per cent).

The Government has nearly reached its target of reducing all classes for five to seven-year-olds in state primaries to fewer than 30, although many classes fo older children are larger. The average class size in independent prep schools is 15 to 20.

Among other reasons cited by parents for choosing private schools were higher standards (21 per cent - this was previously the biggest single reason), better facilities (15 per cent), sports facilities (12 per cent), a wider curriculum (11 per cent) and better teachers (11 per cent).

“Educationists argue about how much difference class size makes,” said David Woodhead, national director of the Independent Schools Information Service, the council’s publicity arm. “Smaller classes mean more individual attention and more personal fulfilment. That is what their fees will buy.”

Independent schools welcomed the recognition by all the main political parties of the right to choose independent education. But they called for types of education largely unavailable in the state sector - such as single-sex and boarding schools - to be made accessible to lower-income families through an “open access” subsidy scheme.

The survey of more than 700 parents found that four in 10 families with children at private schools were “first-time buyers”, where neither parent had attended one, down from half of families in 1997. About half of all families had considered state schools before opting for an independent and about a quarter had other children in state schools.