The Dutch system of streaming children by academic ability has been highly praised by Britain's Conservatives. Simon Kuper, who went to school in Leiden and London, studies the evidence

In high school, some things never change. This morning in maths, all the boys sit at the back, and all but one girl at the front. As they are about 13, some girls tower over the boys. The blue-eyed young teacher - "I've got another 45 years to go" - is the classic object of schoolboy crushes.