Dr Linda Croxford, of the Centre for Educational Sociology, which has a long established record in tracking schools' achievements, told Northern Irish colleagues that comprehensive education had been an outstanding success in Scotland. Over 35 years it had contributed to higher average attainment, lower levels of inequality and social segregation, and less variation between schools.
"Comprehensive schools get a bad press. It's as if they are failing, but they are not," Dr Croxford said.
Northern Ireland has retained a selective system, including a "transfer test" and grammar schools, but is under pressure to change. Dr Croxford said that schools there could avoid the problems of creaming and social segregation that have dogged comprehensive reforms in England.
"On the basis of evidence from Scotland and Wales, we believe that comprehensive schooling has many advantages over selective systems, particularly in terms of equity. A thorough, whole-hearted approach to comprehensive reorganisation is more effective than one which is incomplete and half-hearted," she said.
The Prime Minister last week called for an end to the "one size fits all" approach of comprehensive education but Dr Croxford cautioned that greater segregation and diversification south of the border would increase inequalities.
In England, 83 per cent of schools are comprehensive, against 96 per cent in Scotland and Wales. Parental choice of school added to the creaming effect since middle-class parents exercise more choice and select schools whose intake is relatively advantaged, Dr Croxford said.
"A key finding is that social segregation between schools is greater in England than in Scotland and Wales. In other words, in England there is a greater tendency for middle-class pupils to attend different schools than working class pupils. On the whole, the social mix of pupils in schools in Scotland and Wales is more balanced and qual.
"Comprehensive schools in Scotland are also more middle-class-friendly. Middle-class parents are more likely to send their children to comprehensive school in Scotland than in England."
Judith Gillespie, development manager of the Scottish Parent Teacher Council, told the seminar that the poorest sections of society gained most from comprehensive education, while there was no disadvantage to the most able. Mrs Gillespie advised Mr Blair to keep out of education. "He's a father looking at individual interest and replicating it across the country. His opinions are coloured by his own personal perspective," she said.
However, drawing on her schooldays in the English selective system, Mrs Gillespie said: "My kids went to comprehensive school and did just as well, if not better, academically. But their social mix was so much wider than mine and they came out with good relationships with a whole range of people. Socially, they gained.
"Isn't it always the case we criticise judges for having a narrow range of human experience because they all went to private schools. Private and selective schools are social ghettos."
Dr Croxford said that the CES's research had consistently shown standards of attainment continuing to rise in Scotland, with the increases greatest among girls and pupils from lower social classes. Between 1965 and 1998, the percentage of pupils gaining three or more Highers had risen from 10 per cent to 30 per cent. Average levels of attainment in Scotland are the highest in Britain.
"Although middle-class pupils had higher average attainment than working-class pupils in all systems, inequality was greater in England than in Scotland. In addition, attainment advantages associated with the average social class of pupils in each school were smaller in Scotland and Wales than in England."
Mrs Gillespie said that she did not rule out experiments with specialist schools, but warned: "You have to be cautious that the child is being made to live out the parents' dream." A comprehensive system had to deliver for the majority and avoid reinforcing privilege.
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