Children make more advances when managers and staff have higher qualifications and increased training and experience, Kathy Sylva, professor of educational psychology at Oxford University, said.
The lead researcher on the renowned Effective Pre-School and Primary Education (EPPE) project told an early years conference at Heriot-Watt University, organised by the inspectorate, that the effects of pre-school education last at least two years into primary. Studies are continuing to find out whether there is an even longer impact.
Professor Sylva said the most significant British study into pre-school education showed clearly that the best provision was managed and run mostly by teachers in local authority nursery schools and integrated centres. "If it is not high quality pre-school education, children do not get that initial boost when they enter school," she said.
She recognised that in Scotland this may challenge local authorities and the Scottish Executive which are moving to more flexible forms of pre-school provision as the nursery nurses' pay and conditions dispute staggers to a national conclusion.
Falkirk Council has, for example, approved a revised model that will allow senior nursery nurses to take over key classroom duties as teachers are lined up for more mainline tasks in the early years of primary. The authority would leave headteachers in overall charge of management and quality assurance.
Nationally, the Educational Institute of Scotland and the General Teaching Council for Scotland challenged the Executive over its removal of the statutory requirement to have teachers in nurseries.
Professor Sylva stressed that "you get what you pay for in terms of quality" and said she had advised Gordon Brown, the Chancellor, that pre-school education was indeed a key factor in reducing social inequality.
All forms of nursery provision benefited children but some more than others. "It is worth investing a lot of money in high quality provision," she said.
Children who had no form of pre-school setting and were brought up solely at home were most at risk of developing special educational needs, according to teachers who assessed them two years into primary school.
Findings from a longitudinal study of more than 3,000 children in six authorities in England and Northern Ireland are now showing that children are more co-operative and less antisocial when staff have higher qualifications. Teachers tend to have better interactions with children, offering more direct teaching, asking questions, demonstrating and modelling.
Professor Sylva said that after two years of formal schooling, pupils with better pre-schooling had higher attainment in early reading and maths and fewer behaviour problems.
"It has been shown that a child with behaviour problems at the age of seven is going to cost the local authority an extra pound;80,000 while that child is at school. But it does not cost pound;80,000 to have high quality pre-school provision," she said.
Children who had a good start to school tended to do better. "It's the fact that the expectations and the virtuous cycle get set in place at school entry."