BLUE Gate Fields junior school in Tower Hamlets, east London, has produced "spectacular results," Nicola Sturgeon said as she toured its bright, welcoming classrooms. No one could argue with her assessment. It is ranked in the top 20 per cent in England for attainment in grammar and reading and in the top 40 per cent for maths. For a school in one of the most deprived London boroughs, the results are truly impressive.

Blue Gate Fields was a good place for the First Minister to study the "London Effect," the extraordinary transformation in the city's schools since the late 1990s. In 2000, 35 per cent of London pupils achieved five or more GSCEs, the main exam taken at 16 south of the Border. A decade later, the ratio was 62 per cent. London's results were below the English average; now they are the best in the land. Not surprisingly, educationalists around the world have taken an interest in the London Effect and Ms Sturgeon's announcement of a Scottish Attainment Challenge, inspired by the London Challenge initiative, was widely welcomed. The London Challenge, launched in 2003 by the then Labour government, has been credited with making a major contribution to the improvement by encouraging collaboration between schools across the city.

A recent report, however, suggested learning the lessons of London's success and applying them in Scotland will be far from straightforward. Last December, the economic think tank Fiscal Affairs Scotland took a look at some of the research that has been carried out. One study, from the Centre for Market and Public Organisation, concluded the improvement was largely down to the ethnic composition of London classrooms. It found "higher pupil aspiration, ambition and engagement among migrants". Pupils, the study concluded, came from families who in many cases had left behind more comfortable lives in their countries of origin and were determined to use education as a route out of deprivation in Britain. The CfBT did highlight the positive impact of the London Challenge but found other initiatives such as Teach First, a scheme to recruit talented graduates into teaching and place them in schools in disadvantaged areas, also had a big effect.

Another report, by the Institute for Fiscal Studies, also noted the link between ethnicity and improving exam results, though it was more cautious in its conclusions.

Weighing it all up, Fiscal Affairs Scotland said high concentrations of ethnic minority pupils "can improve attainment levels" but were no guarantee. The think tank also warned it was unclear which policies - the London Challenge, Teach First or others - contributed most to raising standards. As folk in the research business often do, they recommended further research. The FAS said thought should be given to encouraging higher migration, given Scotland's ethnic minority population (four per cent of the total) is tiny compared with London's (40 per cent). It also called for a special focus on early intervention and urban poverty.

Ms Sturgeon has won praise for her willingness to take the best ideas from around the world but we are still only starting to understand the lessons from London's schools.